A Strange effect on iPhone6 and iPhone6+ when I Swipe Left-to-Right and Right-to-Left on Home button twice
This is a feature designed to bring the top of your screen into reach when you are using these new larger devices with one hand.  It's actually activated by a double tap (not press) on the home button.

Check out the item "Reachability" on this apple page:
https://www.apple.com/iphone-6/tips/