I had a run through and it looks pretty good so far. I got a stalkyard vibe from it, which is a good thing. The fast speed, flow, tons of overlooks, and the way the map seems to double back on itself will make for great games. The completed areas looked rather nice as well. Additional stuff:
-I would be careful about that generator that spits out energy balls. It spits out balls too fast and too often, and any jerkoff can just sit there firing a constant stream of them all over the place. If they are efficient enough they could even lag the server. It will certainly make moving through that area difficult because you always have to be wary of a stray disintegration.
-The hallways looked terrible. Obviously the map is still under construction and those areas will probably be the last to be touched, but they really need more detail. Perhaps you could use the shield texture as a sort of overhead window and show some rockwork above them.
-I can get rather low FPS for many of the big rooms due to high swap buffers. This is probably because my graphics card doesn't like the combine refracting windows or maybe just because of the fog. Personally I'd ditch the fog (if its the cause) and use the gained framerates to add more brush detail to the rooms.
-Throw some of those plastic tubes into some areas to add some variety. You could have a room with a big open rock area and have tubes snaking up into the distance, like it's sending stuff to a combine facility above.
-I just today made two prefabs that you might be interested in. They are meant for combine control rooms in normal buildings, but you could probably find a use for them. First is a gun rack from the game and the second is based on what I think were supposed to be manhack storage/dispenser units that were in one of the buildings in Water Hazard. They aren't completely release-worthy yet as they need more testing, but if you want them I can give you a download link.
All in all this looks like the beginnings of a great map.