I have an iPhone 4S that has been out of use for well over a year (but with service still being paid). It still has iOS 6.1.3. While I have always been quick to update my firmware in the past, I was temporarily holding out until I knew more since some of my family members complained about the new interface for SMS/etc. on iOS 7, but most of my apps will not update without a firmware update. What are the major differences between my current OS and 8.1.2? What new features will be available to me on the iPhone 4S? Thanks!