-first couple of levels had a big focus on surviving and working as a team
-levels felt well thought out
-had nice little 'extras' to find, if you paid attention
-last level or two felt way too easy, but especially the 'rescue' level
-that ending..... I get what you were going for, and I liked the idea, but it just doesn't really work as-is. Maybe rework it a little?
Great map, I especially love the first 2 levels. Best played with friends, though, because the bots have a tendency to go over ledges they shouldn't be going over, and either dying or getting incapped because of it. I don't know how much control over the behavior of bots you have, but they kept jumping down the shaft rather than using the ladder.
The last couple of levels felt easy, especially the last level during the hold-out.
I don't know how much control you have over the ending, so I dunno how hard it would be to go back and work on it a little, but if it's possible, I'd suggest doing so. Like I said, I like the idea, and I get what you were going for... but the part with the zombies feels too... static.