Quantity over quality.
I liked the first one, but this one is crap when compared to it. The enemies don't have guns, so they just swarm up on you and try to punch you, which makes no sense. And since when could someone get his body blown off and still walk up to you and throw punches? And why the hell do I have to shoot them 10+ times with the damn SMG to kill them? Why do they take 3 headshots to die?
Then most of the guns are useless. The only ones worth using are the shotgun and the second pistol you get. But, I got sick of it before I could beat it, so I don't think I got all of the guns.