I played it for an hour or so this morning and I think it's alright. I think if it wasn't for Gears 2 and Left 4 Dead, this would probably be the game I spent most of my gaming time with, but yeah, I'm not buying it.
I like:
The limbs flying off
The dogs
The single-shot rifles. I was a beast with these on CoD2.
I don't like
The levels in the beta. They're bland as fuck.
About 90% of the weapons.
The tanks/vehicles. A pointless addition I reckon.