Hmm, I've just got to defend the game here:
a) This game is dark. Too dark. You can't see anything or make out any significant details. The much vaunted realistic lighting model is wasted because most of the game is dark. Even cranking the brightness and the gamma (through the console) helps little.
Agreed, it is dark, but I thought it was just right in that respect. Personally, I tweaked the gamma and contrast settings using the ATi driver utility and got it to where it looks just right. There are quite a few well lit areas, but I feel the dark atmosphere is not only integral to the game, but also showcases the engine by using dynamic lights (ie the imp's fireballs, swinging/moving light fixtures, and quite a few other things).
b) The enemies are dumb dumb dumb. The don't follow you through doors, they only have a couple of routine "evade" procedures that are easily guessable.
Their AI is not great, I agree. But I don't think they're really supposed to be smart - they're supposed to come at you and try to kill you. They do sneak up behind you from dark corners and the like fairly often, though. It keeps you on your toes. Realistically, though, do you think some scary hell demon is going to duck behind objects and try to snipe you? No, they're going to do a frontal attack. Also, they do follow you through doors -- I don't know what you're talking about in that respect.
c) The weapons have an irritatingly long reload cycle and the auto-reload function doesn't work until you try to shoot again after your clip has run out. Weapon sound effects are weak too.
Again, the reload time is part of the gameplay. It adds suspense, IMHO.
d) The actual environments are lacking in detail. The textures are great, but in terms of interesting geometry and fantastic looking set-pieces, there is a lot of boring architecture. They environments are also tiny, it's (so far) strictly a room-per-room sweep with little sense of either being or going somewhere.
Again, I can agree with you, and I definitely concur that things can get a bit monotonous at times, but I think all the moving, glowing machinery and the like is pretty cool. Also, I haven't gotten to the more 'hellish' part of the game yet, so what lies there remains to be seen. Really, though, do you expect an industrial research facility to be full of wonderful architectural design?
e) Little or no interaction with the environment. Glass does not break, monitors do not shatter and lights are invulnerable. Except where it is scripted, your weapons have little or no effect on the environment.
Agreed. The alpha actually had more stuff going on in that respect. Maybe they had to done it down for performance reasons? I expected the physics engine to be much more complex than it actually is. Although, there is a fair amount of breakable glass, and the lights are not invulnerable. In fact, just about any light will break after you shoot it a couple of times. There are a lot of moveable/shootable objects as well, although not to the degree I expected (I wanted to be able to shoot down shelves and see the contents fall off, which doesn't happen).
f) Damage is way out of proportion. The number of times your character can be hit is insane. Also, it sometimes seems like there is a health pack or armour rechage around every corner. I'm yet to run out of armour (or die for that matter) - I've even passed up the chance to pick up armour on more than one occasion because it was full.
Yeah, normal mode is a bit easy. Try hard, it's a bit more entertaining. Also, I'm not sure where you're at in the game, but the tougher enemies come out in force later on. I haven't tried nightmare mode yet.
g) When you are hit by enemy fire, your aim is thrown and your vision impared. This sometimes makes it frustratingly difficult to finish off basic enemies. Coupled with point c), it makes me feel like you are getting hit "artificially" - to make it seem more challenging than it is. I guess this is why your hitpoints are so high.
I like that effect, personally, but if you don't, it's possible to turn it off via the console. Although, again, realistically, don't you think that would happen if you just got swiped by a big demon?
As for point h, I agree, the enemy patterns do seem a bit predictable at times, although not always.
Regarding the engine and modding, I disagree. This game is built for modding, and you'll see lots of mods crop up shortly, I'm sure (although the netcode will need some improvements). The engine isn't 'optimized' for corridor environments -- that's just a matter of content and making the game run on a variety of computers. Just as with every iD game in the past, you'll see mods with bigger and more detailed environments - they'll just take more horsepower to run well. I don't think the engine will have any problems with outdoor environments at all, although you might not end up seeing levels with the scale of Far Cry or Tribes. Ditto with the physics / interactivity. The code is in the engine, and I'm sure upcoming games and mods will use it to a greater degree as time goes on.