We've been a happy paying Testelf customer since I first learned about it on HN several months ago. We save so much time by just sending over our beta builds without having to write exhaustive test cases, and we've gotten back extremely thorough reports. Since the initial mvp they've added awesome features like animated gifs of complex repro steps and full crash logs for crashing bugs. It's not a drop-in replacement for unit testing + customer beta testing, but it's a quick and inexpensive addition to any QA process. I recommend this to every iOS developer I know, it's seriously awesome.