I am still having fun in L4D and I hear L4D2 is on its way. My impression is it's just new maps and players but basically the same game.
one review says
(gametrailers)...Featuring new Survivors, boss zombies, weapons, and items, Left 4 Dead 2 offers a much larger game than the original with more co-operative campaigns, more Versus campaigns, and maps for Survival mode available at launch....
More, more and new, new... but basically the same same. Ill stick with the first title for now.
trailer..