does this driver carry big performance git on 8800gt for example?
Too little of a delta to accurately say that there is a performance increase. Maybe a 1- 2% spread that can be easily dismissed as regular benchmark variance that can occur even benching the same driver twice with the same benchmarks.
I have a 8400m gs on my notebook and 7300gs on my desktop. Both seem to be running fine on 173.08 drivers. In fact, I didn't know there are 2D issues until I read it in Phoronix forums. Perhaps there are issues as window moving seems to leave a trail. But frankly, scrolling is acceptable (even n gmail), though it could be faster.Pretty usable overall. I don't play UT2004 where most people complain about. But I do play Doom3 and it seems to be all fine.
All said, I must add that I am a more or less a pretty satisfied Nvidia user. And correct me if I am wrong, at the moment, Nvidia cards are the only ones which support compiz fully.
And I was surprised about Intel. A lot is said about their working drivers, but to my shock, it was nowhere near perfect when I used it. I had xorg 7.3 (xorg-server 1.3.0.) and xf86-video-i810-2.1.1, which are not too old on a friend's dell notebook with intel 945. The shadows were white. Serious problems with video. Most notably if I move the movie window, the movie stays in the original position until moving is complete.
About ATI - I tried the fglrx 8.471.3 on my sister's intel imac with radeon x1600, and seems to be all good without composite. With compiz-fusion, there is terrible frame-tearing. The only way around was changing video-out from xv to x11 (which is presumably software-rendered and looks pixelated). Hopefully, they solve this and also help the AGP card owners .