Finally works for me too!!! (Samsung serie 7 chronos, ubuntu 12.04)
I had to remove the ppa and reinstall the driver. All seems to work well, I can switch to intel graphic (simple with catalyst control center).

It is normal that only unity 2d works, unity 3d require more resource that integrated graphic doesn't have. (IMHO Unity 2D looks very good in this version of Ubuntu!)

Thank you very much!!!