doom III, from everything i've seen, looks frickin clean as hell.
i remember when doom II was all the rage, adn then being somewhat disappointed with quake. not that it wasnt a huge upgrade in technology, but... i didnt really dig the midieval theme at first (especially when i was so involved in the cool "satanic alien" theme of doom). took me a while to get into it.
at that point, i just figured quake was doom III. to hear that doom III is finally coming to the pc screen is really cool (tho i prolly woulda enjoyed it a lot more a few years ago)