This immersion was tempered pretty quickly, however, by the relatively slow performance of the game running on the demo systems. I don't know the specs of those boxes, but whatever they were, the game didn't run smoothly enough on the demo system I used for truly playable deathmatching.
I was also thrown offthough not necessarily in a bad wayby the shadowing in the game. Way more than once, I came trucking around a corner and unloaded a few gallons of lead into the wall trying to take down my own shadow. Obviously, good players will have to learn to be aware of how shadows are cast in certain kinds of lighting (or at certain places in each map) in order to avoid making this mistake. Shadows should be deliciously creepy in the single-player game.
Speaking of creepy, the Berserker power-up is a blast. When you grab it, your character starts screaming like a banshee, and your view of the world becomes distorted. (Reminds me of hitting the moonshine too hard in Redneck Rampage.) You run twice as fast as everyone else, and you can frag folks with a single punch.
All in all, though, Doom III multiplayer didn't seem as refined as I had expected. Perhaps it was just the low frame rates, but this preview didn't have the feel of a nearly finished game. Several of us who played together thought the player speeds were a little too slow, which detracted from the gameplay a bit. No doubt the final product, on the latest hardware, will be betterwhen it's done.