Doom 3 has been out for almost a week, and I managed to get my hands on it a few days ago. I have to say, it is pretty much the creepiest game I've played yet. The engine just drips atmosphere and tension. While other games (FarCry) use similar technology, Doom 3 just pushes it's lighting tech to the limits.
Crap, I'm starting to sound like Ad, but really the game is pretty kick ass. It doesn't bring too much new to the table, it just does what it does so freaking well.
I will admit though, that half the fun was getting the darn thing to run properly. The game barely ran on Medium Quality, but after some driver fiddling, config file tweakin', and a few other tricks, I managed to get it very playable on High Quality @ 800x600 on my system: AthlonXP 2600 | 768MB DDR Ram | Radeon 9600pro. I may drop down to Medium Quality @ 800x600 just keep a more consistent frame rate, but we'll see.