I LOVED both L4D and L4D2. My gf loved watching the single-player campaign because she likes horror movies, and the multiplayer - even with randoms - was almost always fun and very much free of the usual bottom-feeders who haunt Xbox Live. And I played all the DLC for both. I really love that Valve's most recent DLC for L4D2 includes all the L4D levels. Basically, it's 500-odd Microsoft points for DLC and the entirety of L4D. That's pretty rad.