Not sure if this is an iOS topic or iPhone 6 Plus topic. When I upgraded to 8.1.3, I noticed the little arrow indicator (location services in use) always appear... and when I check in the privacy section its the "motion calibration"... is this common?

I noticed my location services icon kept popping up and the culprit was "motion calibration" after updating to 8.1.3... wonder if this is the issue.

I am using iPhone 6 Plus 64GB on iOS 8.1.3, I'm having this issue whereby randomly when changing camera mode from video to photo, or front to back for example during transition it should blur out then come back clear right?

Mine would get stucked at the blur part randomly... problem can be replicated at times by keep changing the camera modes, photo --> panorama --> video --> slow-mo --> time lapse --> etc then it will eventually get stuck. Only way is to either back to home then start camera back or at times I need to kill the camera app and wait.

Yeah, been having that since 5S... 6 Plus behaves the same way too.

AFAIK the power button was the "weakness" of iPhone 5 which got redesigned in the iPhone 5S though...