Pros:

 - Good design
 - Few bugs
 - Good placing of items

Cons:

 - Very small and restricted area

Conclusion:

It's a little hard to fully recommend this map since its so small, however I can see the potensial here if some changes are made; like a little area above ground with a couple of houses would have be nice. The only "bug" or "hitch" I came across was a little hole beneath the water right before I alerted the horde, it might become a serious problem when a horde is comming. Sadly my friends couldn't join when i started testing and the AI is a bit "stupid" so my review might not be fully judging, but as said earlier; this map has a potential and that's why my score is a class above 50.