If you've updated to iOS 10, or plan to, the following article is quite comprehensive about all the changes incorporated therein. Although complete, it is lengthy and you might feel as though you've started a course of learning that will take a semester to read and comprehend. Jim Hamm
http://arstechnica.com/apple/2016/09/ios-10-reviewed-theres-no-reason-not-to-update/7/