Post button idea [iOS7]

It has been a while since I shared an iPhone app design. Here is an early stage design for new app I can't tell much about yet.

I say Hello to iOS7 with this project! Here is primary post button idea. Having a thin-circle-cutout, so the background (map, photo, etc.) makes the button pop out.

Feedbacks are most welcome.
Cheers, @Oykun