I just got through playing the map on UV without cheats. I survived, but it was one difficult map. If I didn't find the BFG secret I would have been doomed.
Okay... time for comments.
As Lutrov71 already mentioned, there are tons of texture mis-alignments. Myself, I fix them as I go, others... they save them for last, either way it's still just fine.
Now this is a very difficult level, if I didn't act quick after a trap was activated I would have been clobbered. At one point, you grab the Blue key and a horde of monsters attack you, I saw a switch immediatly and pressed it to get the hell out of there. If I didn't see that, I wouldn't have stood a chance. This map is very deadly, but it is okay according to the CC2 rules, so I'm not complaining. In fact, the challenge kept me on the edge of my seat and having a great time.
Your detail is excellent, the map looks beautiful so I have no reason to complain. The mountains are a bit bland, but heck, they're mountains! That's what mountains are! (Except for Death Mountain hehehe...)
The ammo balance is pretty good, it is tight in one or two spots like at the beginning with the ravenants my shells were dropping very low, but it is still acceptable. I only ran out of Cell ammo and that was because I was BFGing Archies the big bad SpiderMasterMind (although he only takes two close range blasts).
Health, on the other hand, isn't balanced well enough. I found myself running around with 50% or less health for most of the level. Because of the big monsters, this is not good, because almost any of the monsters could kill me in one solid hit. I recommend either upgrading some stimpacks, or adding more health (and yes, I found the SoulSphere. It didn't last too long though...).
Traps, traps, traps, this map is all about traps. At least you make them creative on occasion and not the usual trap door, or floor lowering trap. You tend to trap people inside a restricted area and then start teleporting enemies in on them. The only problem is, just about everything is trapped. You get the last key and trap! You kill them, walk a little ways towards the exit, TRAP! Then after that you go kill the SpiderMasterMind and walk a little further down the mountain, GREAT BIG FINAL TRAP! I'm not saying it's a bad things, but maybe you could just teleport them in early so it isn't a trap, but more things to kill every once in awhile.
I didn't notice any actual errors so the map works perfectly.
Well now that I've given your map my throuough review... go finish it and give it to CadMan. I really had fun playing this map, good job chopkinsca!