With iOS 9.1 Apple adds in better support for Live Photos. When someone shares a Live Photo to your older device with iOS 9.1 installed you can press on the photo in the Photos app to see the Live Photo.
Apple also adds an option for developers to support Live Photos in apps so we may soon see Live Photos on Facebook and in other apps on the iPhone.
The iPhone 6s and iPhone 6s Plus are the only Apple devices that can take a Live Photo, but with iOS 9.1 you can see them on other devices.