To summarize the other 200+ message thread on this issue:

There seems to be an odd problem with the documentation package that is part of this update. If you have removed all of your User Guides from the Documents folder on the built in memory, the scripts that run when the package is installed fails halting the installation half way and leaving your tablet desktop in an unstable state.

The way to recover is to just fall back to the old firmware flashing method, do the two pending SSUs (unless there is already an updated firmware out ... there wasn't when I ran into this issue) and then restore from backup using the backup utility (you did do a backup when prompted to before the SSU, didn't you?).