I'm on iOS 9 public beta 4 on my iPad Air. I've tried iOS 9 public beta 3 on my iPhone 6 plus for a few weeks, and then reverted to 8.4 more than a week ago.
Beta is prereleased software and should be in stalled only on devices that are not used for personal or business as in many cases it can be buggy slow and unstable. I personally would wait for the release as it is not far away