So far the new maps seem like their missing the polish of the original games.  Bland textures, lack of ambient objects, etc.  This somewhat changes once you get to the second map and see the insane amount of options you have for paths to the end.  That Fallen Survivor is going to be the dead of many a' parties when some jerks tries to run it down for a bottle of pills, lol.  Avoiding spoilers I'll just say that the interaction with the L4D 1 survivors was kind of disappointing.  The big plat twist goes unmentioned and almost unnoticed unless you really look for it and the original gang doesn't even mention that it happened (unless its in some of the random saying I haven't heard).  All in all, its definitely worth the money for Xbox Live players and you'd be insane not to get it for the PC since its free.