Haven't seen this on launchpad yet but:
Laptops with Intel graphics chips, post upgrade may not be able to enable desktop effects (compiz). May also get a warning during boot of "low res mode".
The problem is during the upgrade, all sorts of Nvidia drivers were installed, and they're clashing with the Intel drivers. The workaround (I know of two times this worked perfectly)
sudo apt-get --purge remove nvidia*
You may want to apt-get -s first (simulate) and make sure nothing unwanted is being removed. Then reboot and Bob's your uncle.