I have tried to play it before and got really disappointed after the fight with the first boss. The cut scene especially annoyed me. I mean, who the hell walks right into the middle of a very suspicious room and just stands there looking at something creeping at him? So I stopped playing there and thus didn't see the rest. But now, when I've seen the complete game, I truly have the right to say that it just sucks. Why, you ask? Well, let me see... It's named Doom 3, so it should be a Doom game. And since Doom games started with Doom (Ultimate) and Doom II, they pretty much define what Doom is:
* Doom is original. It is not like any other game. Doom 3 is not, since it is pretty much a random horror FPS shooter.
* Doom is beautiful. That means: beautiful monsters, beautiful textures, beautiful places. Remember how monsters looked in the original games? Remember hand-shaped map? The citadel? Tricks and traps? Circle O'Death? I can continue. Doom 3 has nothing of it. Ugly monsters look like they were taken from a random horror film. Maps look like a random sci-fi disaster game (think Half-Life). And so are textures with some hellish exceptions, however in the original series they were much, much more varied. In Doom 3 it's mostly dirty metal. Where have that skull switches gone?
* Doom is about exploring carefully designed maps. Remember searching for a key in labyrinths? Remember running around the Citadel, looking for a way to get that drat blue key? Remember pushing switches to figure out what they do? There is nothing like that in Doom 3, only some random puzzles which are retarded anyway.
And what is left now? The graphics quality? It's good, but games are not only about quality but also about the art. And besides, how are you supposed to enjoy the graphics quality when you can't see anything around you because of the drat darkness? AI? Can't say it's especially good. Physics? Come on, it's XXI century, nobody is going to be impressed by that. And that's all about the engine (which is good), not about the game (which is not). The game uses some tricks to seem original but they become rather boring very quickly. I mean those spawning monsters and monster closets.
The only thing about Doom 3 I really liked are the weapons. But they are pretty much the same as in the original Doom games. Plus a typical SMG and that weird Soul Cube that makes boss fights rather boring.
Overall, Doom 3 is just another Half-Life, just with the lights turned off. They should have named it Half-Doom or Doom 0.5, that would be more appropriate. I shall never buy it. I would rather buy Half-Life 2, at least it is somewhat fun and beautiful!