I like the fact that they don't have a lot of ammo piles laying around. You have to make decisions on your weapons. Example: I have this nice AK-47 with a laser sight but I'm nearly out of ammo. I just found an auto-shotgun which is full of ammo. Hmm.

Definitely more challenging than L4D. Normal seems like Advanced. Maybe this is just due to the newness of the levels and infected but I think they may have cranked L4D2 up a notch or two.

L4D2 = WIN.