According to Apple:
iOS 8 is the biggest iOS release ever — for developers and everyone else. It means it is going to be helpful and developers with more integrations. But that wasn’t the goal. We simply set out to create the most natural experience. Each enhancement has a purpose. Every new feature deserves to be a new feature. Each function is more considered, each next step is more eﬃcient. It all adds up to an even better experience — one that is pleasantly surprising at ﬁrst and becomes utterly indispensable before you know it.
For the Developers, iOS 8 will be more exiting as it is coming with more keyword buttons options, sharing buttons, images editors with more edit option. So as much as we can do on Mobile, iOS 8 will be there to provide all this setup.
iOS 8 will be Compatible with iPhone 4s, iPhone 5, iPhone 5s, iPhone 5c and new coming iPhone 6
iOS 8 – World’s most Advanced Mobile Operating System
Photos – Easy to Share Across All Devices
Messages with More Sharing Features
iOS 8 KeyBoard with more control and typing options
iOS 8 – iCloud Drive (Any kind of file on all your devices)
Heath Meter – iOS 8 – Fitness information
Release Date – iPhone 6 and iOS 8
Both iOS 8 and iPhone 6 are expected to be launched in September 2014.
iOS 6 – Images Gallery
Note: All iOS 8 images are taken from : https://www.apple.com/ios/ios8/