Doom 3 has very few flaws, which makes this shooter really stand out.
Single Player:
The single player is definitley the highlight of the game. the single player portion will scare you and make you feel like you are really alone. The graphics are outstanding. Unlike anything i've ever seen before. The creatures and demons are incredibley modeled and detailed. And for once, the gore actually looks real. You will feel like you have actually just shot someone with a gun. The sounds effects are amazing as well. You will hear women screaming, babies crying, demons roaring and growling. Your super-smart enemies will jump out when you don't expect it and scare the hell out of you. There is a decent amount of weapons which are all, for the most part, pretty powerful. Especially the chainsaw. The weapons are all very fun to use. You will encounter many enemies, including imps, mancubis, and all sorts of other demons. You will also fight about 5 bosses throughout the game. They are all fun and challenging. Another thing I liked about the game was that there was no music. It was just you in the silence, waiting for a demon to roar so you could go blast it in the face with a shotgun. Overall, I think this is one of the best single player games out there.
Xbox Live
The Xbox live multiplayer was a great addition. The deathmatches are kind of lame, but they also include an epic 2 player co-op mode. This is a great addition and it is very addiciting. You will find yourself on the 2 player co-op alot. Then enemies and weapons are very well balanced in the co-op mode, allowing an equal amount of heart-pounding action for each player. The co-op was a strong addition to the game, and shouldn't be missed by ANY fps fan.
Doom 3 is a very successful shooter that lived up to its hype, greatly. Anyone who lieks fps should by this game. Even if they don't have xbox live.