The graphics in L4D2 are great, the game runs very fast on Ubuntu, Valve has done a great job. I hope more games keep coming to Ubuntu and Linux for Steam overall. I tried the Source SDK recently and the sample builds and runs successfully on Ubuntu. Now as far as game play, L4D2 and TF2 seem similar to me, too Hollywood, I like more muted game play, similar to L4D which I tried on Steam on Wine once. If that was on Linux now I'd buy that one and probably play it more. Also more Minecraft like games where when a grenade goes off you see damage to the walls, ground, etc. and you can build stuff, defenses, machines, etc. that would be unreal.