Works well, suits its purpose.

This app facilitates the beta testing new/upcoming iOS applications by “regular users” and without having to use a custom testing device/platform. Test Flight does exactly that, and does it well. For it to do anything useful, you must be working with an app developer and receive an invitation code for that app, and Test Flight should already be installed when you acknowledge the invitation. If this sounds confusing to you at all, you probably should NOT be using this app or doing any sort of “beta testing."

I haven’t had any issues with Test Flight, although I haven’t been using it for long. So far I am pleased with how easy this process has been.

FCGreg about TestFlight