First time I ran Upgrade Pandora OS, it failed early on after checking for updates (but it always does). Second time, upgrades happened but during the process I got a corrupted message box with the title "Missing resources" and a load of boxes in place of text, even on the Ok/Cancel buttons. Didn't stop the rest of the installation though, which continued in the background.
Edit: Nope, it froze the update in "updating gstreamer" - I waited for half an hour and then had to reboot with pandora+power as everything was frozen. Now it fails to boot, with a complete lockup at the "Please login" screen. Looks like I'll have to reflash