This game felt like a strange mixture of Rebuild 2 and Last Stand, but mostly in a good way. The graphics were good enough and the premise was... no better or worse than your next zombie flash game. I went into this really hoping to like the game.
Unfortunately, the controls are frustrating. I can understand recoil and don't mind that bit of realism, but it's going too far when the recoil of a rifle jars me out of the playable area so that most of my game screen is white with the action going on at the top and the aim suddenly not working at all (thus making me have to waste a bullet or two until the recoil jars me back into normal view). Maybe that's a bug, but it still makes some of the waves extremely annoying.
In reference to not being able to aim at the zombies on the bottom of the screen, I feel like that's a reasonable thing with the rifles. It makes sense in that you wouldn't realistically be able to aim that close under the barricade. You should, however, be able to do so with a pistol since it's a lot smaller and gives more maneuverability.