I upgraded my Ubuntu 12.10 to 13.04 and I'm getting terrible time.
After upgrade (I used terminal version sudo -do-release-upgrade) which worked fine, computer asked for reboot - I did so and the ubuntu didn't started (just blinking cursor and nothing happened) and I couldn't even change the tty by using ctrl+alt+Fx. After hard reset it started well. Then I wanted to install gnome-shell 3.8 using "official way" (gnome3 repository) and it also went ok. But ater reset, lightdm didn't started and "gnome-shell --version" gave me 3.6.1 (and it should be 3.8). I uninstalled everything connected to gnome and try "fresh" install of gnome-shell. Everything worked again (installation), but my theme is broken and I guess there will be maybe more broken things. I tried to install gnome-theme-extra, gnome-themes-extra/standard/ubuntu... But it is still same.
Gnome-tweak-tool says Current theme: Adwaita (default), but it looks like high contrast. Here is screen of my
Next problem is, when I try to reboot PC or just using shutdown through upper-right corner, computer doesn't shutdown. It just hangs at "System is going to shutdown for MAINTENANCE I need tu use "sudo shutdown -h now".