On the previous build, prior to the update, if you held on home and slid your finger up, it would expose the Google Now arc, so you could slide to the "Google" circle and lift your finger to start Google Now. The 12.15.15 update has changed so that all three of the capacitive buttons have this behavior. If you press on the buttons, the normal function happens. If you slide up while you are pressing the button, it exposes the Google Now arc.
My guess is that Motorola was trying to duplicate the functionality of a phone with on-screen rather than capacitive buttons, where a slide up from the bottom of the display launches Google Now.
If you press those button without sliding, you should be all set.
This seems like the most controversial part of the update. Maybe a future update will come that exposes a setting to control this?
As for the recent button sometimes needing a second press to show the running apps properly, that was a bug that existed in 12.7.7 that persists in 12.15.15. It doesn't always happen, but it sometimes does.
With all due respect to the Mod Team Leader, I think a thread titled "Don't do the update!!!!" is a little extreme. But, that's my opinion. Hopefully it's ok to express that, politely.