I upgraded my 3 Friday not long after it was available. I always make sure I'm backed up in icloud but especially Dropbox. no problems at all. A few quirks that I think will get ironed out but... Just go to Settings and choose a background. Mine did not open with white BG AIR but I chose one immediately anyhow, both for lock screen and home screen. i uppgraded my husband's 4s and 2 Apple TVs, one of which bricked but a micro USB and itunes solved that issue.
I love control panel, multitasking cards with ability to just flick an app up and closed since I use so many, itunes Radio, lots of little things i especially like.