My 5s was going at around 2% per minute just on the home screen.
Seemed to stop draining and heating like a boss after a reboot though!
But drain seems slightly faster than B2 on my 6+.
Performance wise things seemed a bit jittery on my 6+ much more so than in B2 - referring to simple animations. - It felt VERY android-esque with the jittery animations but that stopped after a reboot and is a lot better now (but naturally not as good/smooth as 8.4 but that's to be expected!)