Pros:

interesting lab underground.
dynamic lamp police car.
wonderful environment in the last chapter I like.

Cons:

less ammo in the zombie lab.
a little narrow rooms in the building.
a boring finale and short.

Conclusion:

it's waster about 40 minutes,3 chapters,i think it's just right.
this is a hard work I understand,but you have a interesting design.
A new map by u,cheers!