The iOS 5.1 update rolled out to every iPhone 3GS/4/4S and iPod touch that are capable of running iOS 5. Among the new features are Japanese language support for Siri, better Photo Stream management (i.e., being able to delete photos), battery life fixes, and a few other miscellaneous additions.
From my perspective, the biggest fix that Apple made for the new update is for the battery life issue. If you’ll recall, I’ve had a few bad experiences with the iPhone 4S battery already, so I’m obviously incredibly happy that an update that explicitly brings battery fixes has finally rolled out of Apple’s tightly-sealed doors.
I do have my 4S running on the latest software, but I can’t comment on whether the battery is any better, nor can I say anything about the Siri update. But other than the two big things, there are certainly other new additions that make the 206MB update worth downloading.[MacRumors]