I have actually finished the game. The game was played in full with the first official patch installed.
S.T.A.L.K.E.R: Shadow of Chernobyl is a great game that is better than most typical shooters, but it comes up slightly short when compared to HL2.
Graphically: The atmosphere is excellent. The living world that surrounds you is something you won't find in any shooter. The character models, particularly of the other stalkers, is what I found to be most dated and more could have been done to improve them.
Sounds: While the sounds aren't mindblowing, they are well engrained into the atmosphere. Some of the yells and screams are truly distressing.
Gameplay: The guns and their accuracy is debatable. Some will like the inaccuracy of some of the guns since it forces you into close combat. Some of them are really inaccurate, which will also cause many to be really frustrated. There are mods to fix this! Other than that, the controls are for the most part standard FPS. I had to replay many levels due to amount of enemies and their superior weapons, although you get some nice ones close to the end of the game.
Story: The story was too disjointed. It gets better as you get to the end, but it could have been presented in a better way. The PDA also needs improvement.
Overall: Stalker polished, would have been at the HL2 level. I still enjoyed it, though I wish the ending had been grander. There is already a big mod community out there, which can only increase the value of the game. The last missions are particularly intense and enjoyable. Hopefully the developers will continue along this path and continue to bring fresh material(with a little more polish).