Let's get something out of the way first. Yes, I am a game developer (thus subjective), but I also play a lot of games - primarily on PC. I have probably played a vast majority of the games that are out there. Therefore, I think I also have the right to expect something special from 6 years of development and a budget apparently exceeding 40 million dollars - even more so since I have some idea of what 6 years and 40 million can get you in terms of development time and development budget. Has HL2 fulfilled my expectations? Not at all. In fact, it is a miserable disappointment.

6 Years in the making - 10 hours in the playing
First, the game is relatively short. Take away some puzzle sections that required you to go back and forth on the same level a few times, the boring helicopter fights and the sections in which you sit and can't do anything but watch, it could very well be even shorter. I am not one for long, drawn out games, but somehow I kept going through the first few chapters thinking the plot cannot possibly be that the pet headcrab pulled out a cord out of mischief and that's why Gordon has to traverse 3 chapters through sewage pipes (thus accounting for a fifth of the game). Then, another "twist" with Gordon getting stuck behind a collapsed wall and having to go through an 80'es B-horror flick (Ravenholm? More about that later), even though sitting next to Gordon was a robot capable of lifting a combine barricade. I guess those barricades are made out of some space-age polymer and probably weigh less than a pile of rocks. And while I was waiting for something to happen - blam - the long awaited and hyped striders and - the end level (sprawled across three chapters, of course).
Don't get me wrong - I do understand that Gordon needed to be alone in order to play out these chapters. But, I cannot buy such weak plots and they only weaken the atmosphere that is portrayed in the game (one of a rebel force trying to organize an uprising). They had to be more plausible and believable - not all of us playing these games are 12 year-olds.
During those 10 hours, the environments and playing fields do present some variety. Gordon is on foot, then on the speedboat, in the car, with some people (members of the resistance) and then finally alone again. This is probably the best aspect of the game and the only thing that has been delivered. Some sections are a bit too long, but overall Gordon does change method of transportation or environment about where you get bored of the one you are playing in.
I read some reviews of HL2 that said that the campaign is about 20 hours, but I tell you right now - that's not true if you are a reasonably good player. Since the battles and enemy encounters offer little variety, you will pass them on the second if not the first time. I can honestly say that I probably died about 30 times in the whole game (playing on Normal difficulty) - and most of the time from radioactive slime or a fall to the death. The only reason why this grade is not a 100, is the shortness of the campaign and the fact that you can learn the enemy encounters by heart (like in old coin-op games).

Blend-in' in the wind
The visual aspect of the game is never a make-it-or-break-it thing for me. I have played enough games that looked decent and played fantastic, and enough games that played like paint dries but looked great. Playing these games on a Dell Inspiron 8200 Notebook, it is more important for me that the game scales well (primarily downwards :)). HL2 looked pretty decent on my Notebook, in fact it looked good enough that I was able to focus on the gameplay and immersion - my two more favorite elements in the game.
I did however have some slowdowns in some sections, primarily when explosions were nearby, and a very aggressive LOD default setting. Rigid body objects and generally non-essential decor blended into view a few meters from my eyes. Some people might mind, but for me it was not a big problem - and if it bought me a playable frame rate - then bring it on. Of course, in the late chapters, when I would try to pull in a combine enemy using the gravity gun, he would disappear in one frame, and then his dead rigid body would blend in when he got closer. That was a little weird, but not a big deal.
One thing that was really well done were the character gesticulations and the lip-synching. I daresay this was the best aspect of the whole game for me - how characters would be able to make and break eye contact with Gordon. This was particularly good on the friendly characters. The whole body animations were only good for the friendly characters - the enemies were ok, but had their bad moments. Overall, I think we got pretty much what we expected from the visuals of this game.

Music and sound
Sound, equally important as visuals, is not equally of as high quality. While it is evident that Valve spent a lot of time and effort (and disk space) in various taunts, NPC talk, story progression commentary and what not, a lot of the game comes out sounding the same. Combine soldiers - although I am sure they use more than one sound file - always sound like a lotta static. And does this ring a bell: "Sorry Gordon", "Let me get out of the way, dr. Freeman". I have had nightmares about those lines. Not to be overly critical, the cut-scene audio is not that bad, but it all sound just a little bit B movie-sh. I mean, contrary to popular opinion, I think people would rather watch an A movie than star in a cheesy B movie. Maybe a big portion of the problems I personally had with the sounds in this game is because it was so set-up and didn't really follow the dynamic of the game well. For example, you would have citizens of City-17 give you some "leave-me-alone" phrase early in the game for 5 minutes straight, and then you hit a trigger, and they are all panicked and getting shot and generally in you way. It all just looked very unnatural, and sounded bad too. The music - one word - terrible. It never seemed to go with the action and was always just a touch too modern for my personal taste. I don't necessarily think that they needed to do orchestral score for the game, but having cheesy post-modern music over a dramatic piece of action is too much day-time television for me.

Why it plays completely bad?
Ok, you have arrived at the meat of this review. Gameplay is absolutely the most important aspect of a game and this game has completely blown it. I can only speak for myself, but I was not waiting for HL2 for six years in order to see cool graphics - I was waiting to see "the next generation" of gaming. How unfortunate that when I played HL2, it played like some older game - hmm, let me think - oh yes, Half Life.
Yes folks, it is exactly the same. While some people might say this is a good thing, there are but 6 years in between HL and HL2, and other people have published games as well, so I don't see how Valve thought what they had to offer with HL2 was good or even sufficient. I will focus on every particular aspect of the HL2 gameplay and explain why I think it belongs in 1998.
Lets go down the list:
THE LEVEL DESIGN: I have read that it is brilliant, that it gives the player a sense of freedom and that it gently leads the player in the right direction. This cannot be further from the truth, and only shows that the authors of such epithets for this game have no clue whatsoever. The levels in HL2 are what I affectionately call "sausage designed". That name comes from my old Macedonian language teacher who used it to describe a written paper that contained only one long paragraph. In the case of this game, what it means is that when you unwrap all the rooms and corridors that admittedly make turns, what you are left with is a large corridor in which you cannot move any way but forward. There is absolutely no place for player choice and after some time playing the game becomes not boring, but damn funny. You arrive at a place from which there is no obvious door out - hmm, what should you do now? Valve's answer: the famous and patented LOFTIL approach! There are maybe 4-5 places in the game when you suddenly get to a seemingly dead end - LOOK FOR THE INCONSPICUOUS LADDER - LOFTIL!
Now, I have nothing against linearity, per se. Doom 3 was completely linear, but that wasn't its major flaw. To have linearity stuffed in your face constantly and without relent was really hard to bear. I mean not even two doors out of a building that lead into the same yard. Now for me, this doesn't translate into a player-friendly, understandable game, as some people are so fond of saying. This is just a pure insult to the player's intelligence. It means that the level designers do not trust the player to be able to find his way out of a building if they don't lock all doors except the front door. No guidance, no subtle clues, just dumb pressing on the forward button.
I also read somewhere that the environments were believable. How funny was that thought as I was running along one side of a river canal on a ledge that had no other purpose than to get me moving along the sausage with combine troops spawning on the other side on an elevated position taking shots at me. No - this was believable, and not just some cheesy setup in order to have some inconspicuously stacked barrels dumped on me when I go through some trigger. Really, when I can tell what's going to happen 50 meters before I get to the spot - you have missed the believability mark.
THE CUT-SCENES: The cut-scenes are pretty good (production-wise, story-wise they are terrible). As I said before, the character animation and lip-synching quality are a testament to the dedication of Valve's art team. But the cut-scenes have one glaring flaw - they do not work if the player does not cooperate. Technically they work, but they don't make any sense. Try it yourself - I am a player that wants to explore as much ahead as possible, so it was really funny to me that in some cut-scenes characters would not acknowledge me until it was time for them to do that in the script. A good example of this was the first encounter with the doctor (where Gordon gets his suit). There is some chit-chat between Alyx and him before he is scripted to notice Gordon. All my running in front of him or hitting him on the head with cans and stuff did not help him notice me earlier. Now, this is completely counter immersive for me. And even if I can live with that, then the places in the game where you need to be in a certain position in order for the cut-scene to make sense (like the time when Eli notices you through the monitor) - I was all the way on the other side of the room - how the hell did he see me? Some might say that this is no big deal, but it it a big deal to me - if you are going to represent cut-scenes and have me move around in them as I want, you better damn well make sure I can't break them or just make them not make any sense.
Another bad aspect of the cut-scenes is the ability of the player to move physical objects around. Characters don't seem to care that you drop barrels and boxes on their head, they don't care that you hit them with coke cans - they are just so happy to see you. I am sorry, but wouldn't a simple reaction to this make some sense? This way it feels like - yeah Gordon, you are a murderous maniac and obviously an unstable person, but you are the last hope of the resistance and the most important person in the world. I am always of the opinion that if you cannot do something all the way, then don't do half-done solutions. I am obviously in the minority since this fact did not bother anyone else playing this game.
THE ENEMY AI: I expected a lot from the AI in HL2 - not because of the hype and the cool videos - I know how you can set up something to look good in a video. No, I was excited about this because of the time these guys had to get it right and to make something that would be really unique and challenging - something that would pass MY Turing test and make me think that I am playing against someone who has intentions, a plan - a self preservation instinct for god's sake! - a really Artificial I. Well, folks - there is none of that to be found here.
Ok, I am somewhat biased, having constructed the AI for Far Cry and I even admit that my personal expectations might be a little higher than the average player's. But even with all that admitted, I cannot find an excuse for the really bad performance that the enemies (of all shapes and sizes) have in the game. But lets start from the beginning.
I have had a lot of grief about the sensory systems of the enemies in Far Cry. People were saying that it was too sensitive, it could see too far, it could hear with uncanny accuracy. And this was purportedly a bad thing. I agree! So, how do you like some AI that has absolutely NO sensory perception and is driven entirely by triggers? Because that's almost what you get playing HL2. People were complaining that a trained mercenary could see you from 100 meters away in Far Cry - but at least there, you could hide from him again after he saw you. He was able to lose you and search for you. This gave you the opportunity to use that against him. In HL2, no matter how slow you creep, no matter how crouched you are - you enter that door (read: trigger) - they see you - regardless of whether they are 10 or 100 meters away. There is no place in HL2 for any maneuver on your part (if we do not count the obvious choice of whether or not you shoot that explosive barrel). The enemies do chase you when they don't see you anymore, but even that is poorly done. Early on in the game I learned that I only need to hit the door (read: trigger) and just go back a little in the sausage. They will all obediently come to the door one by one and receive their complimentary bullet.
They do path-find very well, and I was wondering whether to attribute the piling-up-on-the-door thing on the AI system quality or the sausage design. I decided that they were equally to blame, but at the end of the day, it is the responsibility of the AI engineers to offer solutions to sausage designers and condition them to let go of some level control and open more approaches to a potential player position. This is why I write about this problem here and not in the level design section.
As a byproduct of the aforementioned problem, the enemies in HL2 have absolutely no idle behaviors. They don't DO anything. They just spawn around the next corner and stand frozen until you hit the trigger that activates them. Don't believe me? Stop pressing forward when playing HL2 all the time and try to slowly approach sections. You will be able to see the enemies in the next section from the distance, and if you have rockets, you will be able to shoot them and do whatever - but they will just stand there frozen. You will not be able to kill them. Move slowly forward, and you will be able to tell when you hit the activation trigger since the enemies will start running towards you and shooting. An even better way to see this is with friendly NPC's. Get off the hovercraft and walk forward through a tunnel. There are some triggers that are set to trigger only if you are in the hovercraft. So, when I hit those triggers on foot, they don't trigger. So, whenever you need to park the hovercraft and have a conversation with some guy from the resistance - walk there on foot and shoot a few rockets, shotgun shells, throw some stuff at those people - they won't do anything - they will just stand there frozen - not even a breathing animation.
Same problem on the famed Ravenholm level. The priest that has the most useless cameo in the game is dead frozen (when you didn't hit the trigger) even though he is standing on a rooftop 20 meters from your position - you can see that he is frozen, for pete's sake. In combat, the AI has a non-scripted side, in that it does move somewhat free in their little area - where they have navigation points. But the enemies lack a purpose, and all their strafing left and right is useless most of the time (not to mention that it looks bad too). They are also dumb as bricks - they always run towards the explosive barrel. It got old after the second time - so I just stood there and patiently waited for them to get next to the barrel and saved some ammo on shooting them. Plus the barrel was easier to hit.
THE PUZZLES: Ok some of the puzzles were not so bad - but most of them were downright ridiculous. I found the air puzzles especially absurd - when you have to stack empty plastic barrels under water underneath an iron ramp so you can use it to jump over some obstacles with the hovercraft. Anyone who has any clue of physics and the natural world in general knows that this kind of setup would never ever work since the ramp would sink down from the weight of the hovercraft the moment it slides on it. There were a few physical puzzles like these that made little sense, and allthough they did use the physical engine, they still served only one purpose - to break the immersion and to scream to a rational player that this is just a game that lets you get away with the strangest things as long as the designers set them up like that.
THE GRAVITY DEAL: The gravity gun. Some people say that it alone is worth the whole game. I agree that its a really cool weapon and allows you to do some pretty cool things. So then, how unfortunate is it that you don't get to do those things in the game? First of all, it's implementation is completely unfinished. I spent a lot of time hurling stuff at NPC's, inactive enemies and other things that refused to react! You cannot move any of the cool things in the game like large obstacles, cars and things that would make a difference in the level layout (I guess that would compromise the inherent linear nature of the levels). It just boiled down to moving slightly larger boxes than those that you could move anyway with your hands.
Second problem: Anytime you pick up something, it covers up the entire screen - if it is anything that is supposed to do some damage when you hurl it - thus BIG! Many times I found myself picking up an explosive barrel from one area to have an extra bullet when I enter the next area - just to see that it actually impeded my view to such a degree that I finally had to throw it into some wall just to be able to see where the hell I was going.
The bottom line is: the idea of the gun was cool - but in this confined game area and forced puzzles it hardly shows it's true potential. I think people got more excited about the idea than the implementation. 6 years should have resulted with a more finished implementation.
OTHER GIMMICKS: The enemies were largely uninteresting. Implementation-wise, they were lacking a great deal. The much-hyped striders were a big joke as the battle with them rarely lasted more than half a minute - they went down really quickly, especially in the areas where Gordon had some help from the rebels. And anyway they just boiled down to helicopters that moved slower and had a different visual look. After all was said and done, I think the most effective enemy in HL was and still is in HL2 - the headcrab. Especially the new (black) variety.
The ending... hmm - I thought that the ending of Far Cry was not all that - but what the hell was the ending of HL2? No closure, no payoff, just the same thing you got when starting the game - more vague speeches by the GMan. It just screams "we didn't know what to do". And lets face it, game producers think that only 20-30% of the players actually get to the end - so they don't push for it to be really cool - yes kids, that's why most game endings suck.
And the squad - always getting in Gordon's way and absolutely no way to get rid of them, since you cannot bloody well SHOOT them. They do not feel like squad mates, they are completely expendable and most of the time they are a hindrance more than an advantage. If they skipped the whole squad sections, this game would be much better.
Finally, the bugbait levels were pretty cool - I actually was feeling closer to my insect squad mates than the human ones. They were obedient, they didn't get it my way (as much as the humans) and there was always more to pop out of the ground. If only there were any levels that offered some chance for me to develop a strategy for them instead of just running forward and shooting bait.
I played on normal difficulty, and I noticed that the combine were really lousy shooters - they kept missing me from relatively short range even though I wasn't making a particular effort to avoid their fire. Also, didn't anyone in Valve's QA notice that if you just keep driving forward (I tried it with running too, it worked as well) while the insects jump around you - they will inflict very little (if any) damage? That was pretty funny.
So what is the conclusion? The game is average when you play along. If you try to come out of the rail pushing you forward through the game and explore a bit, you will see that the game is relatively unpolished. If you do not cooperate with the game, it gets confused or at the very least looks bad. Examples include combine troops stuck at mounted weapons, not reacting to objects thrown at them, and even not reacting to Gordon jumping in front of them. The whole deal with being able to see inactive enemies was really surprising to me since a little more twists in the level design sausage could have easily eliminated the problem (if you can't see it, it doesn't exist). For these reasons and more, this game gets a miserable grade in the gameplay department.

Story and pacing
The story is nothing to write home about. Just the standard guy comes to the village being tortured by the evil tyrant, guy meets cute rebel girl and wise village elder. Guy defeats tyrant. I don't even know how could someone even proclaim that there is a story there. This story has been perpetuated through films, writing, comics - even my 7th grade friend Goce made a (very badly drawn) comic with roughly the same story. To not be able to come up with something better (I will say it again) in 6 years is by any account a very bad thing.
Just last night I watched a re-run of an old B movie called "The Philadelphia Experiment 2". I had seen this movie before, but after playing HL2 I realized that this movie has the exact same atmosphere as HL2! The wire fences in the City railway station: there! The camera identification line of the citizens: there! The bloody combine (sans the Jason masks): there! Even the boring propaganda commentary in the City background: there! Please go out and rent this movie ASAP and see for yourself that you are being served an 1993 B movie as a AAA game story and setting.
I found this great quote on this internet site that sums up my opinion about the story in HL2 : ("Some originality wasn't unasked for, you know . . . "). In this movie you will find Alyx (albeit black), the Doctor and a device that can teleport people between remote sites. Great work, guys!
The pacing is a different deal altogether. The game goes from a frantic chase into a puzzle solving section just because you passed under some bridge. Action can go from me throwing boxes, furniture and anything else I could find on a standing combine troop without getting a reaction from him, to having people suddenly running past me yelling "Combine troops" because of that same troop, that now decided to shoot me. Things just happen as - hmm, what's the right word.... Ah yes, that's it - TRIGGERED. And that's what is actually happening, folks. I was just surprised that Valve did not do anything to hide that into some story gradation, or even a small cut-scene or whatever.
Finally, because I was able to notice all these things, that indicates that the game lacks a veneer of polish. Now, if more time can't get you better gameplay, at least it can get you more polish. This game is less polished than other games that were developed on less budget and less time (for example: Mafia).
There can be no excuse for this.

Conclusion
I hope it is a little clearer why I say that this game was a big disappointment for me. Ultimately, I only got into game development so I can make THE GAME that I always wanted to play - cool, believable, immersive, intellegent. Honestly, I think every developer, when faced with the degree of expectation and hype as Valve was, naturally falls back into well established routines and plot lines - averaging the final experience out for all of us. And at the end of the day, I am just one person. HL2 got really rave reviews and probably sold very well. But that says nothing about the quality of this game, it just says a lot about the criteria and general common sense of the average game player and reviewer. I guess it is really true what a friend of mine (also a game developer) told me once: Players don't know they want something until they are playing it.