For those on iOS 8, please hold on and not run the 8.0.1 patch that Apple just pushed. It has been reported that it is causing serious grief causing these issues:
What defines a great User Experience design? In one short sentence, it is “whether it simply works or it simply does not.” Many iPhone users are loyal to their devices simply because they feel that it works. While some pundits may bemoan using two hands and the ever-so-slight fragmentation that will inevitably occur due to the different resolutions between the 4.7″ and 5.5″ variants – it remains to be seen if it will be enough to topple the UX of iPhone. Perhaps a closer look should be paid on the exact feature that makes iPhone UX such a firm favorite among Apple users.