Pros:

I personally like starting out tier 1's.
Map 1 and 2 are challenging
Like the "point of no return" in some of the maps
Finale is huge. Lots of places to cover and lots of places to spawn.

Cons:

Not enough Dialogue

Map 2- Don't really see a point in having a lid to be open after going through the houses. 

Map 3- no panic event and the routes should be more difficult

Map 4
Panic event is a little weak. 

Map 5/finale
Second tank didn't show up and the waves(commons) was weak. 

Conclusion:

Its really good. Just needs a few adjustment to be made. The story is interesting.