We just downloaded the new Android 2.1 release and upgraded 2 phones but it was definitely an afternoon project.
When you install this, your phone is wiped clean, everything except the SD card was trashed.
Here's a list of what we had to do:
Downloaded the Android 2.1 binary installer (.exe)
Downloaded the latest HTC Sync software
Use new HTC Synch to update Windows calendar and contacts
Verify GMail is synch'd with all Google contacts
Downloaded MyBackup (or similar) from the Market
Using MyBackup, made a backup of all our installed apps and data
Ran the Android 2.1 binary installer
Waited what seemed to be forever for the phone to reinitialize
Using MyBackup, restored all apps (each require an install) and data: EXCEPT *DO NOT* restore Android Home from the old version (wife accidentally clicked "CHECK ALL") and it whacked her HTC software and she had to start over with the installer.
The only problem we ran into is the stored browser data, login names and such, were missing plus data in a few other random apps.
However, all the music, pictures and everything else were still intact so there was some additional work reconfiguring apps and such even after the restore.
Maybe this is why Sprint's still holding off releasing the upgrade, trying to get a complete backup/restore procedure in place.
Perhaps they're just waiting for the rest of us to do all the work and guide everyone through the process like I just did above to avoid the landslide of tech support calls.
Either way, it's a marvelous upgrade and I'm still discovering new things Android 2.1 does, well worth the update even if I have to enter a little data here and there.
First Impressions on Android 2.1 from an Android 1.5 user:
I'm hoping my carrier will be rolling out this update fairly soon. I was one of the early adopters of the Hero. I had to do an update already just to get 1.5. It sounds as if 2.1 is a major improvement.