It's a good map. Solid theme, fairly well optimized, and really fun to play. Me and my friends had a blast! The only possible improvements to me are:
1# In the first campaign, on the right side of the bridge and tunnel right outside the safe area, you are allowed to backtrack behind the buses and cars which leads to a dead end. I personally think it should either be blocked off, or you should hide a little secret back there.
2# L4D2 weapons don't spawn in the saferooms
3# In the third level, it wasn't very apparent where to go. I think the orange arrows guiding you should be larger and more abundant.
4#In the last level there are death triggers in-bounds, which can be easily walked into.
Aside from that the campaign is great. Keep up the good work
Good map, I just have a few small gripes.