iOS 9.. The biggest feature will be optimizing and performance/bug fixes. 5-15 percent bigger battery casing. OLED screen with force touch. A9 faster and smaller diei chip. If the 4.7 only lasts 11 hours on wifi. The 6S 4.7 will get around 16 hours. Sounds crazy but I am certain for those 4 reasons. It makes sense.. I wouldn't be surprise if it lasts twice as long maybe even up to 22 hours on wifi. But that's if they use all 4 strategies. Who agrees ?