So far the upgrade has been only positive for me. If you do the backup first then the upgrade is very easy. About the only thing I had to do manually after the upgrade was to re-edit the .opera/input.ini file to get the page up/down button functionality I prefer.
There used to be some automatic reboots in the past (although only while idle), we'll see about that I guess. So far 'uptime' reports 2.5 days up.