I'm on the fence with it. I agree with everything you guys have said, so I'll just jump to my issue with it. I'm use to it going back to the app I'm on. It was handy to quickly glance at another app (like if I'm needing to copy something down but the app is preventing copy/paste selections), then tap again to go back to what I was doing. So there's that habit to break. Now the other issue is when I tap it the first time, it drops the current app all the way down so it's barely showing on the screen. So I'm also now having to try and adjust where I'm tapping to get back to what I'm doing.
Minor annoyances I know, but old habits and muscle memory are hard to break.