The only better thing in radeon is faster X startup and a lot faster suspend and resume process, but I think this will be solved in fglrx with the time too. After all, fglrx is consisted of both open and closed source code (as far as I know).
And I didn't experience any faster 2d performance with radeon than with fglrx. The video acceleration is the same. The only difference is when I turn on compiz effects - then fglrx makes no 2d acceleration at all, and radeon 2d performance is faster. But with compiz turned off, radeon driver is no match for fglrx, except in multi-monitor support. In multi-monitor support, radeon driver is a lot better, but since I use my laptop mostly for browsing the web, watching videos, gaming and for study, I rarely use multi-monitor feature.
So, to conclude, fglrx is an excellent driver for me (in comparison what it used to be one year ago).
Happy New Year to everyone!!!