my few small but simple applications. In past I've done ad hoc releases and distribution manually and was not really looking forward to do it again.
Then I was told about TestFlight. It's beatiful. It's user-friendly. It works. And then some more!
Just one reminder: you still need to add each tester UDID into your Apple Developer iOS portal account devices section, regenerate and download distribution profiles. About everything else is taken care of by TestFlight.
End-user installation happens Over-The-Air, which basically removes 95% of all ad hoc release issues! When considering how simple and easy using TestFlight service is, it's a wonder Apple hasn't bought them yet!