Thoughts and comments:
The first window - for the room with the camera monitor - you can shoot through the window - even though there is translucent "glass" on it.
I think there should be something in the alcove on the other side of the river (where the shotgun guy is). I'd go for a secret or something.
Put something in the pool at the bottom of the waterfall (and change that texture dammit

)
In the small corridor with all the angles on the floor, one wall has a different Y offset to the others.
The angled floor / ceiling things use different textures in the N/S versus E/W section. Is this intentional?
The lift room looks cool. It raises the standard for the map. Unfortunately, it makes some of the plainer rooms look, well, plain.
The broken lift idea - some suggestions. Instead of just telling the player the lift is broken, make it feel broken. Make it stop slightly before it reaches the floor, so the player cannot get off. Then make it drop a few units, stick again, maybe add a little, short duration quake - wash and repeat a few times until it reaches a point where the player can get off. Combine this with a creaking steel sound and by that stage the player should know to get off the damn thing without any text clues. When it eventually drops, if the player is still on, make sure they get killed at the bottom. Changing the sector damage to something very high would be an easy way to do it.
Heh, WTF is going on outside that window? You know, the one with the water. It looks like there is some strange sort of mid air floating river/pool just hanging there in space. If you want to make it look as if there is a huge watery area outside, with the sky coming down to the water either make the area much, much bigger, or try experimenting with linehorizon (line type 9) on the lines that bound the area to see if that gives the effect you want.
And finally, you have done some cool areas and some very nice stuff. You clearly have some interesting ideas. However, it seems the reason for the map existing is simply to go from one cool area to the next without a unifying theme or reason. Is the map just evolving as you think of something cool to add (as it seems), or do you know where the map is going?