Been playing the slasher class with the perk that allows you to stand up after 5 seconds of being pinned/incapacitated, and have noticed that if an enemy (particularly the creeper) incapacitates you and isn't killed (say, if you're away from your silly bot team mates) it can instantly attack you again when you get up, before you have any chance to do anything. I'd imagine it's the same case if there are a few regular infected around you. Kinda defeats the purpose of being able to get up again, doesn't it?
I think it'd be a nice improvement to add a second or two after getting up where you're invisible to all enemies, sort of like how the masking grenade works. I believe this is what L4D does.