Unless you're running bootcamp, I wouldn't agree with you. Even more so if you happen to be running 10.6.7 on OSX, as it's already been reported to be a known issue with decreased graphic performance. And again, I'll disagree even more if you have your Air plugged into an external display.
Don't underestimate the Air for gaming, especially at native resolution. The proof of it's pretty exceptional gaming capabilities are well documented all over these forums.
I've never read any report... not saying none exist... i just didn't read any. I literally put on Portal 2on my 64gb MBA just to see... it runs like crap, even when set to the lowest setting about an hour before I posted that... and then I deleted it.
It's a great little machine and I'm sure it's satisfactory for most... but I won't ever be playing games on it again. Bought it for web browsing email and to write. That's all it's going to be for.