Apple: 66% of devices supporting iOS 9 have it installed
The adoption rate for iOS 9 is now 66%
Besides the 150 additional emoji that comes with iOS 9.1, the update also allows the Apple iPhone 6s or Apple iPhone 6s Plus to sense when it s being lowered or raised. This prevents the rear camera from recording the phone being moved up or down for the Live Photos feature. With Live Photos, your iPhone camera records video of the 1.5 seconds before and after you snap the shutter on a photograph. So when you look at the photo and press down on the screen to activate 3D Touch, you see a 3 second video as your photograph comes to life. The feature is available only on the two latest iPhone models.
source: AppleInsider
Things that are NOT allowed: