Well, i also have Mobility Radeon X2300, running Ubuntu Gutsy on Asus F3Jr laptop and I did and upgrade from 8.1 fglrx using the automatic installation.
So far tested:
xv - finaly works, no blocks or diagonal tearing, even HD demos run fine, it also uses noticably less CPU
3D - tested glxgears and fgl_glxgears, all works, score +- the same
suspend - tried a few times, seems to work
hibernate - not tested yet, worked on 8.1 but with dead sound
compiz - no luck but it has never worked in the past,so its perhaps some configuration mess on my side
