Glitched...But not bad
Just from my playing, I found a handfull of glitches: Sometimes I would lose the ability to shoot, sometimes after dieing I'd still be dead when I retry and wouldn't be able to shoot, and after retrying, I would come back with a weak barricade.
Overall though, it wasn't bad. Personally, I found it a bit too difficult in that it took forever to kill the zombies. I'm not sure if that's just an issue with me not knowing how to aim or if they were made that way. It's not a bad game though, don't get me wrong, I just think it needs some tweaking.