Just a share of experience on update to lolipop 5.0.2. After upgrade via OTA, the battery running like linear line, phone is easily heat until i take few shot of photo and camera is shutdown because overhear.

After factory reset, every thing so far so good. battery usage no more linear line. Phone temperature is back to normal. Able to take more than 10 shot without any issue.

Note: THe restore process is painful. I have backup using PC Companion from Sony. After the factory reset, I have try to restore all my application from PC Companion. Then only it prompts certain number of application data cannot be restore because the application is not installed.
Moral of story, although you have backup using PC companion, it does not backup all the application. You need to re-install the application from google play. Then only you can restore the data from the PC companion.