Even the surprise! factor wouldn't be as big a deal if the game was half as long or even a third as long. We wouldn't have been quite so tired of the whole thing, and it also could have saved some of the monsters. Zombies? Great. Imps? Good stuff. Just don't use them exclusively for two hours straight.
id really stretched the length of the game out far too much. New monsters are always welcome, but the time between introducing them was far too long. Plus, for the most part they were introduced only one at a time. You start with the basic zombies, then add the fatsoes, then zombies with pistols, then zombies with shotguns, then zombies with assault rifles, then some basic demons. Each monster is absolutely milked dry of any personality or mystery before the next one is introduced. If the game had been half as long, none of this would be a factor.
surprise! imp behind you!
The developers relied almost exclusively on their surprises. Being scared and tense is great - the first night I played was and will be one of my most memorable gaming experiences ever. However, by the second day when I started looking for benchmarks for Brandon, it became apparent that that's all that id was trying for. They missed so many opportunities for pitched battles and stand-up fights. Even the few times that a big fight seemed to begin, it was only to distract the player from the demon that teleported behind him or the fatsoe zombie who came out of the closet. Utterly predictable and a real shame.
During the Deus Ex: Invisible War review I mentioned that it was a good game but not so great an experience. The opposite is true for Doom 3. It's a poor game but a great experience. It relies on one trick too much - but that trick, in addition to the graphics and sound, is capable of maintaining the experience for several very tense hours.
The most painful thought is just how close id got to making a classic. By adding more straight original Doom-style fights against the monsters, with no lame attempts at a surprise, would have improved the experience tremendously. A half dozen scenes with the player fighting alongside fellow marines would be the definition of coolness. One or two eerily quiet sequences without any combat, any spooky noises - say 3-5 minutes at a time - could have built up tension to an unbearable level.
As it stands though, it's almost as if the designers chose "copy, paste surprise teleport imp" and randomly distributed it through the levels 100 times, then repeated the same for a closet zombie, a cacodemon floating up from the ground or down from the sky, or a ceiling-crawling demon. "surprise" my ass.
id, hire some women. They know the trick - to always leave someone wanting a little more.