With no official change-log, the hunt is on to find the new features and improvements in the phone. Already added to the list is an auto-switching mode to give you a Qwerty based on-screen keyboard when you move to landscape mode, and some more reductions in the UI of the highlight-tap/double tapping that is a carry over from 3rd edition.
As always, please back up your phone before doing a firmware upgrade. Although your data should remain intact, it is never guaranteed!