Well, graphics are awesome, game runs nice and smooth.
Humor is great, loads of swearing, but funny.
So far got 2 weapons and the leash. You get these base stations all over that you can buy ammo and upgrades etc.
The pistol I got is sick, dirty Harry style
Killing enemies is awesome fun, you can shoot, kick, kick then shoot, kick them to death, kick them into things that kill them. Its epic.
Sometimes though it does feel a little too easy, but there were some parts that I had to re do about 5 times because it was pretty hard, so there is a nice balance.
I honestly would say that even if I finished it this weekend and never played it again it would have been worth it. Its something totally different. I am dying to play the MP. I am sure that is also great.
Edit: O ya and the gameplay can get manic sometimes, just shit flying all over, bullets, baddies the works
You can either run in fast and kick the shit out of everyone, or hang back and headshot guys. Either way its fun.