Joomla 2.5 upgrade issues

Joomla 2.5 upgrade checklist, essential if you are not wishing to have a disaster .

do not think this is a quick job to be done last thing on a friday evening. I say this in case you run into issues you are then left with no back-out time.
do the upgrade in a test area so as to verify it completely before moving to live.
backup your site and make sure you can restore from the backup successfully. Remember a backup is only 1/2 the job a successful restore is the full job.
make sure all your existing components have joomla 2.5 versions available
make a list of all admin and frontend functions that are currently working
make a copy of all the site urls in case they get mangled on the update and you end off with 404 s from google search results
if you have made custom changes to these components get out your list of changes, ( you did make a list right ! )
make sure the restore of the backup works
use the joomla 1.7 upgrade feature in the admin
after the upgrade check all functions are working in the admin and on the public site.