Great for your first game
Now, if the sequel fixes all the little problems and adds some nice things above and beyond this game it will be amazing.
Everyone tells you what's great, so here is what I had problems with:
-Sawed off shotgun was glitchy. It should reload automatically after the 2nd shot instead of making me click a 3rd time.
-You should be able to switch to your other weapon while reloading instead of forcing you to go through the loading animation while your barricade gets killed.
-The higher level weapons don't seem to be any better. For example, I thought the Uzi was better than the 2 assault rifles. I used the sawed off shotgun until I got the last weapon. Even with only 2 shots it still killed the enemies faster than anything after it, except the final weapon.
-My computer sucks...if there was an option to have the corpses go away faster it would greatly improve the game's performance.
The game ended right on time, because after I got the final weapon there was no challenge at all, so you did a great job there and didn't overstay your welcome. Great job for your first game. You'll be getting my flash of the month vote.