Hi Ho:

Just wanted to report that I've been upgrading my sites to Joomla 1.7, and all is going well so far.  I like the one-click upgrade!  (One of the few advantages that Wordpress had over Joomla is now gone.)  In the course of my upgrading, I have discovered a couple things I thought I would share:

• I noted that item identifiers in Joomla menus had changed from IDs to Classes.  This was a pretty simple fix in my CSS.
• I did see some language .ini files get overwritten, so you probably want to make backups if you've been customizing your language files.

Other than that, the backup went smoothly/as expected.  I haven't done this yet on any sites with lots of third-party extensions, but I soon will!