Pros:

-Really Well Made Map
-Plot Driven Survival Map
-Forced Teamwork
-Challenging
-Variety
-L4D1 Bots Helping You Out.

Cons:

-No warning when the bridge is about to break. (-1)
-The bots are really stupid in this map (EX:they jump in the field where all the zombies spawn and get killed.) (-5)

Conclusion:

Overall, this is one of the best zombie survival maps out there, definitely worth a download.