iOS 10 PB1 so far so good on iP6s+. Surprisingly stable considering how buggy 8 - 9 were. A lot of stuttering for 3rd party apps but performance wise still normal. Battery life is actually quite good.
I can't get emojify to work though. Also, press home to unlock does need some time to get used to. For this post, the keyboard also doesn't auto change from the symbols/numbers page to qwerty when I press space (which is the case in iOS 9).
Overall very pleased with this beta. Hopefully Apple will squash more bugs and push out an even better beta soon!