Pretty poor!
This wasn't a great game, I'm surprised it got front page to be perfectly honest. I though it was interesting how you differentiated between story mode and survival, as after what was the story? Two people find a building, and stay there shoot endless hordes of zombies? Poor effort on that front!
As for the gameplay, it was O.K at best. Graphically I thought it was good, and it controlled well, but it was too easy. All you need is the P90 and your set, especially if you sit by the window in the bottom left hand corner.
Improvements for a future sequel? Increase the difficulty (more expensive weapons, lower accuracy, tougher zombies), and add A STORY! (i.e. different settings along the character's journey to some stronghold somewhere, i don't know, what ever you want).