I was on 8.1.2 jailbroken and was having major issues, notifications weren't coming through, dropped calls, missed texts and emails. It was a disaster. I've restored multiple times and setup as a new phone jailbroken and still had issues... I tried 8.1.2 stock and still problems. I got tired of it, and after saving my shsh file for 8.1.2 with tiny umbrella I restored to 8.2 and it fixed some of my problems however since I owned my 6+ I haven't killed it as much as I have while running 8.2... I lived with my phone completely being dead every day even with little to no use. I would get 12 hours of use consistently on 8.1.2 and any version prior with my 6+ and on 8.2 I was struggling to get 6 or 7 hours. Same apps, setup the same, and horrible battery life... Now 8.3 releases and I update without question. It was much better for bugs, but it still was struggling to get 12 hours daily use. TLDR - I did a DFU restore, then did a regular restore, setup as a completely new phone. DO NOT restore from any backup - set itunes not to sync your phone. And for the last 3 days I've hit 12+ hours of use consistently.