Having the same problem ... I didn't force mine to update just woke up for a snooze and saw it was there, which is probably why I didn't think to back everything up beforehand ...
Were you using voodoo rootkeeper? I'm wondering if that is the source of my problems ... also using pattern lock weirdly enough, that can't be it though, can it? ...
Anyway, I created a thread before I remembered there is separate devices sections so I could have checked the Nexus 4 one (there doesn't seem to be any posts about our issue in the android 4.3 one) ...
http://forums.androidcentral.com/and...ml#post2961706