For me personally, my issues are -
As soon as I got home and plugged the phone into itunes, it started chirping and hissing and buzzing while sitting on the couch next to me. I was looking at something on my laptop and thought 'what's that noise?' I first thought I had a window open and I could hear insects buzzing around outside. It was then that I realised it was my phone. It has not done this since.
When I put my ear to the back of the phone, I can hear a noise pretty much identical to what is in that video above. This doesn't really bother me though. I never pressed my ear to the back of my iphone 6, for all I know it was doing the same thing.
When I record videos, I have lots of white noise and a very high pitched buzzing noise too. Different to the above video.
I also have a scratched camera lens - even though I have been extremely careful with it, as I have been with all my phones. Haven't had a case or screen protector on an iphone since the 4. Never even had a scratched screen, forget the lens. I noticed this scratch within a day.
http://imgur.com/STOrmPy