My iPhone worked fine on the iOS 10 beta 2. Apple advises it won’t work any of the beta versions of any software, except during the test periods. The phone worked fine from my perspective and being lazy; I didn’t want to perform the update.
A couple of weeks ago though, the phone occasionally prompted with the message “A new iOS update is now available. Please update from the iOS 10 beta.”. Finally, over the last few days this prompt appeared every time the device was unlocked. Eventually, I decided to upgrade the iOS to the public version.