Having just upgraded my iPhone 4S to iOS 6, I figured I’d share a few things I learned and a few annoyances I’ve found.
Passbook is pretty much useless until there is more 3rd party support. Currently only Fandango, Live Nation, Lufthansa, MLB.com At Bat, Sephora to Go, Ticketmaster, and Walgreens are supported.
If you choose to set email signatures by account, you must have a signature for each account on your phone or it won’t work.
With auto-brightness, the screen sometimes slowly dims on when you unlock the phone.
You may have noticed that the ability to share Reminders lists disappeared from iCloud.com when it was updated. You can now share lists from the Reminders app in Mountain Lion 10.8.2 (I don’t see a way to share within iOS).