I know this is an old topic but I had to put my two cents in. The Go Pro cameras have gotten better and better over the years. The quality of video you can get from the Go Pro Hero 3 + (I do mean specifically the +) has gotten dangerously close to something that could be used along side other high end professional cameras. I personally have been using a Hero 3 + on a DJI Phantom with a Zenmuse gimbal and a pair of Fatshark FPV goggles to see what it was capable of. I have been mostly pleased with the results and feel that it could provide me an easy affordable way to add some aerial shots to the content I produce.
I love the protune mode and Camera Raw White Balance (although I do notice slight color fluctuations for some reason) and these are great additions for people who want to use this camera on a professional level. However, the major thing holding it back from being ideal is exposure control. I simply cannot understand those who cannot grasp the importance of this. If I am using this camera to simply document an experience such as surfing or skydiving, than sure... I love the idea of auto exposure. But if I am trying to meticulously film something on a professional level then I really don't want my exposure jumping all over the place. It gives it that distinct, "Shot on a cheap auto camera" feel and makes any serious color grading a pain. Anyone who does any sort of videography on a professional level can appreciate having full control over your image.
As much as I would love to have full manual ISO and shutter control (I believe the iris is locked at 2.8?) even a simple exposure lock that would let me lock it and dial it in with a slider via the LCD screen would suffice. This camera is so close to be something amazing and I do hope that they at least add these features into the next edition.