Chad Williams has a great list of features in iOS 6 that are new that you may not have heard about:
The auto-dim feature got significantly improved in iOS 6. The best improvement is brightness adjustment in the lock screen. Before, in a dark room, I would be blasted with the iPad or iPhone’s default brightness before sliding to unlock and having it dim down to match the room’s brightness. Now, from the moment the screen turns on, the brightness is appropriate.
It is the little things.
/via The Beard.