I like it and don't like the duct tape mod. Its cool because you actually get to see some of the details of the critters, but it also detracts from the suspense of going in the dark areas.
I've been thrilled with Doom 3 though. IMO, a MUCH better game than Half-Life, which was phenomenal in its own right. Far Cry was weak though- while the graphics were great, the weapons did piddling damage (4 point blank shotgun blasts to the head to kill a HUMAN!?!?), and the enemies could snipe you even while you were concealed in underbrush. Doom 3 has a lot of cool horror/sci-fi elements, and strongly reminds me of Event Horizon, which was a great atmoshperic movie. I finished the game tonight, and the cyberdemon is terrifying. But what really weirded me out were the spider centaur demons. The arch-vile is really nasty too, although I wish they would have made him resurrect dead monsters like he did in previous Dooms, but since the corpses disintigrate to ash (another great effect), I can see why they settled on summoning. The Hell level is really freaky, and gave me some great visual and aural cues the next time the group I DM for faces demons.
The only complaints I have are that the monsters don't make very different types of noises or bellows unlike the old Doom- they all do that screechy hiss thing. I also preferred the old shotgun *BOOM* noise to the new one, but overall these are minor things. Finally, I wish more monsters would appear in larger open areas, kinda like the old Dooms. But it is cool that if a critter shoots another, they WILL rip into each other. Overall, an incredible game!