Not true, Both times I have updated in the betas (1&2) I chose "check for update" yet I still had to restore from backup and sync.
anyways, pretty cool.
Go into settings and double check your firmware version. If it's true, that's pretty awesome, but I very highly doubt any of the firmware installs would ever only take 5 minutes and not make you have to reinstall everything from a backup. It doesn't just "upgrade" the firmware, it overwrites the whole thing.