I ran the Natty upgrade again today from my backed up maverick root.disk using the daily Alternate CD (January 12*). There are some interesting changes. For one, lots more errors during the upgrade including one saying the whole upgrade failed. But it didn't.
And a nice change is that as I logged in - forgetting to switch from Unity to the Classic desktop - there was a popup informing me that my hardware did not support unity and, would I like to switch to classic? Great! It didn't work, but a good idea all the same - and I assume it will work soon.
So after re-creating the 'logout launcher' I escaped Unity and switched manually to Classic Desktop and then it logged in fine (apart from having to reload all the crashing panel objects.)
Here are some pics from the upgrade process. The following popup appeared at least 3 times (and might have something to do with the fact that Natty has my keyboard set up as USA/Afghanistan now) ...
This one looked serious:
This one sounded like it was toast:
Despite the serious message - the upgrade worked, Natty booted first time... and nothing too exciting has happened since.
* I ran the upgrade from the daily image of the Alternate CD on January 10 and January 12 successfully. The images shown are from Jan 12; there were no material differences that I've noticed between the two. When I attempted to do it on Jan 11 it wouldn't allow the upgrade to begin due to some package with an incorrect version. The message is, if you find that the upgrade fails one day, just wait and try the following day (this is normal for alpha testing since the repositories are updated frequently and sometimes packages get out of synch). Also, be careful if you are offered a Partial Upgrade when running the Update Manager in Natty. Sometimes this is required but often it's an out of synch set of updates so it's best to be sure - use apt-get update and dist-upgrade to figure out what will be removed and decide whether it's an error or required.