After going through the livecd process which was smooth and uneventful, when it came to the reboot back into the installed system, all I got was a blinking cursor on a black screen.
This is caused by Grub not being installed properly, for whatever reason.
The solution was for me to mount my filesystem (/dev/sda1 in my case) and use the "grub-install --root-directory=/mount/point/ /dev/sda" command. If I didn't add the --root-directory option, it would fail.
Rebooting again allowed me to log in.
Not impressed Canonical. I'll keep going with this OS for a bit, but when it comes to reliability and usefulness, I stick with Gentoo.
Update:
The problem is with one of the raid packages, as this also occurs on Debian 7 in the same situation. It's not an Ubuntu-specific problem, but upstream. Still, with such a blocker for an install, I don't see how it could have crept through TWO different distribution QA phases.
