I'd put it down to the phone doing lots of stuff in the background like indexing things for the new search and Siri functions for now. This is always the case after a major update on OSX for me and given the changes in iOS this time around, I'd put it down to the same thing.Give it a day or so, then see how the battery is coping.
Topic:
App & System Services
SubTopic:
Core OS
Tags: