HomeLan was among the lucky folks who got the chance to play a four player Deatmatch demo from Doom III. This one will also be played at QuakeCon. Here is a quote from HomeLan :
Visually, Doom III looked very sharp. We couldn’t find out what the hardware specs were on the demo machines, except that it was running at 640x480 resolution with no AA enabled. Despite this low resolution, Doom III is one of the best looking PC games we have ever seen, with very detailed character and weapons models, some incredibly realistic level textures and of course the Doom III lighting model, which makes dark spaces very dark indeed. You can even shut off light in certain areas in order to high from opponents.