I played it for about an hour after it finished d/ling and it runs pretty good on my 6800GT. The load time improved astronomically when the download was done, but it still has long load times. I had stuttering in 2 spots in the beginning but after that it hasn't happened since. I had a weird super slowdown when I reloaded after I died but I didn't continue playing because it was 4am then so I had to get some sleep
. I like the game overall though I wish they used a different engine. The source engine is OK but overall I never really liked how things look in it, there is just something off with it.
From now on I need to preload everything I might buy on steam. The insane 42kbps d/l on release day just sucks, and it made me think I would have been better off buying it retail and finding a no-CD crack.