I downloaded and played the new Crash Course DLC for Left 4 Dead with some co-workers last night.
Very different, in that there are pickups (weapons, ammo, etc.) freaking _everywhere# (at least comparatively). It's also very short, plays fast, and throws a lot more special infected (notably, Tanks) at you.
I'm curious as to which of these gameplay tweaks are a nod to those changes in L4D2.
At least it gives you new, interesting achievements, and I still need to check out the online additions to decide how angry I am about paying ~$7 for the DLC ("degree"; not "whether").