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So far seems good. Many of the enhancements are totally non-intuitive to trigger, but once we get used to them I can't imagine we'd ever want to go back. So far seems fast and stable enough other than Outlook is totally crashing on launch.
 
Performance is great and battery life is a lot better than 8.4.1 for me. I'd definitely say to update.
 
Been running iOS 9 through all betas and now on 9.1, runs flawlessly! iOS 9 was built for the iPad Air 2 and the iPad Pro. Getting about 14 hours usage with about 111 hours of standby.
 
I never updated my iPad 2 to iOS 8 after all the horror stories. But I decided to update it to iOS 9 because we don't really use it a lot anymore, but pleasently surprised. It seems to run iOS 9 as well as my iPhone 5 does (which isn't really fast but oh well I'm upgrading to a 6S soon).
 
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