Sometimes after the upgrade, you might have a problem with the X server not starting (the machine hangs with the Ubuntu logo on the screen right before you are about to see the graphical login prompt) I had this problem with my install, so I rebooted, pressed "Escape" when prompted (early in the boot process) to enter the menu. I selected "Recovery Mode" which landed me at a console prompt logged in as root. Next I typed

apt-get install xserver-xorg

then

dpkg-reconfigure xserver-xorg

This basically reinstalls the X Server (gives you a graphical desktop) and reconfigures it. This is a bit of an oddity, but I wanted to include it in case it happens to you as well.