iOS 9 is coming for free to iPhones and iPads tomorrow. Focusing on stability, user experience as well as bringing increased security features and improved multitasking and split-screen functionality for the iPad Air 2 (and upcoming iPad Pro). Updaters will welcome a number of new things about iOS 9. For one thing, it is a smaller download and should take up less time (and valuable storage space).
iOS 9 requires 1.3GB of free storage (instead of the 4.58GB of the previous version). iOS 9 is also supposed increase battery life on most devices (Apple promised 1 hour during WWDC). Having tested the public beta on an iPhone 5, iOS 9 does seem smoother and a tad bit faster. The new OS is expected to roll out tomorrow through the Software Update setting on their iOS devices.