I am curious about the 3D touch first hand. Also this is a first iPone which has the13 MP camera. It has been at 8 MP since iPhone 4S. It would be interesting to compare and see how much one can squeeze out of mobile phone’s camera.
The major disadvantage of iPhone, from my standpoint, is the one and only physical button, double-clicking which one can switch between application. Both Android and Windows Phone provide much more advanced and convenient ways to operate a device. I am very eager to see if the iOS 9 and 3D touch would deminish or eliminate that tremendows weakness of the iPhone. I posess over 2000 apps in iOS, many of which are unique, i.e. do not exist for Android or Windows Phone and I am very much interested to assess the chances of staying with iPhone.