Pretty good
I played it all the way to the end but a few things annoyed me. The barricades were too weak, I stopped repairing them because there was no point anymore. The turrets, though useful, would no shoot outside of the fortress. If a zombie was standing right behind a barricade the turrets would not shoot at it. That kinda pissed me off because i found myself constantly baby-sitting my turrets so the zombies wouldn't break through the barricades. Aren't turrets supposed to help you secure the area? How can they help if they can't efficiently operate while in a different room. Another thing that bothered me was the lack of reward for turret kills. Maybe it was to balance the game but i found the turrets of stole most of my kills while i was near them, so I earned scarce little cash while baby-sitting the things that should be protecting me. Overall it was fun to play, but all of these thing made it a lot less than what it could have been.