Faster Access to Apple Pay
Apple Pay is one of the nicest features on the iPhone 6 and iPhone 6 Plus, but opening Apple Pay can be annoying. With iOS 9 you can use it faster with a double press of the home button while the iPhone is locked.
This is like the Apple Watch, and it is one reason we've used Apple Pay on the Apple Watch more than on the iPhone. With iOS 9 a double tap opens Apple Pay and a swipe can change your card.
Apple is also adding support for store cards with iOS 9 and finally Discover will join Apple Pay this fall.