I am doing the same but with another phone, the lumia 1020, because of the money, because I hope the quality of the pictures is supposed to be better than go pro, and because I enjoy the dyi involved.
For the moment I am more focus on videos. I tried several setups but, in very bright conditions, jello is there, so not worth on sharing anything.
How did you manage on taking stills? Are you using an intervalometer?
The good part is that, even though I switch airplane mode on, I can use an app for GPS tracking, and it works very well, i have the path on Google maps, the altitude and speed graph...
Would you share your setup?