iOS 9 is a system that is considered unique among mobile systems that supports old hardware, this operating system supports iPad 2 and even iPhone 4s, both devices came way back 2011, though iPod Touch support up to fifth generation models.
One thing that we like with iOS 9 is that even your four year old phone can be installed by this system. But for newer devices, this will be a different story to tell, in the present we only see some improvements on the device performance, example the Java script rendering. But there are not major improvements on 3D rendering.
In the positive side, notable change that we noticed with the device, the battery life for instance is tough. Imagine a phone that can last up to seven and forty one minutes of non-stop music play back and web browsing. Take note that was for iOS 8 and for iOS 9 it is somewhat increased by more than one hour.
The increase of battery life to almost two hours when upgraded to iOS 9 is a great advantage already. This have exceeds company’s claims of just one hour in battery life after upgrading to iOS 9.