After a regular update Ubuntu 12.10 to linux-3.5.0-19 today unity did not work anymore. The grafical environment starts, wallpaper and desktop-icons are appearing but all that unity-stuff will not work.
I knew this problem from an other PC, where it happened some weeks ago after the installation of Ubuntu 12.10. The reason was an old ATI grafic adapter and I had to install ATI legacy driver to make it working. Due to the developer decision that Unity always needs 3D-acceleration
On my actual Notebook I changed the ATI driver from propritary fglrx to the open ATI display driver and now unity is working. Too bad, that this open ATI driver is buggy and does not start from times to times.
I think Ubuntu loses control with that version 12.10. Unity is allright for me, but it is not ok that they give up the 2D mode and quit working in an emergency environment. The effort for maintenance is getting so high since Ubuntu 12.10, that I am thinking about alternatives.