I installed it on my 6s Plus last night and the battery drain was terrible. It went from 81% when the update was done to 15% in an hour. Thinking it just needed to sit a while, I charged it over night and within an hour of unplugging it at 100% it dropped to 80%. I'm in the process of restoring my iOS 9 backup.
I installed it on iPad Pro and iPhone 6s plus, its way too smooth for being a beta, iPad Pro is blazing fast after this update though it was fast before as well but now its even faster, I haven't noticed any serious bugs or problems yet.