Mine upgraded without a hitch.
Out of an abundance of caution, in addition to my Time Machine backup - I dragged my 56gig iPhoto Library file to an external drive, checked/fixed any permission issues, and rebuilt the iPhoto 09 database (holding down CTRL/OPTION when starting) - before attempting the upgrade. Worked like a charm! Finally got Faces to work (which I probably could have fixed a year ago if I knew how to rebuild the database in 09).
Will be trying the other stuff in the coming days...