Ok today installed amd 12.1 for my onboard amd hd 4250(880g chipset). It has both some good and bad thing for me.
1. Video on vlc has been smooth. I had a nasty bug that full screen video(any resolution,any format) on vlc or mplayer or any player suffers lagging started since I update to Kubuntu 11.10. But if the floating panel is on(put the cursor on it so that it not disappear) then its smooth. Now this bug seems to gone
2. xvba back va is working goodly. It was corrupted before.
3. On Google chrome accelerated 2d canvas still give no visual error(it give that before). With it demos.hacks.mozilla.org/openweb/HWACCEL/ is giving 60+ fps. Without it gives 23 fps. Although Amd is still blacklisted by chrome 16. I have to use about:flags to unblock both the card and accelerated 2d canvas.
1. Looks like 12.1 has some performance regression at least for Lightmark.
2. Not new thing but today I saw it after installation that kwin is not using GLSL shaders nor direct rendering(both are ticked at kwin cofiguration). Kwin was giving some minor performance issues since 11.10 on resizeing window and some here and there randomly. Don't know if its causing by this or is it always direct rendering was disable for my onboard graphics.