I've heard a lot of praise for Testflight, and now we have people proclaiming "I wish they'd charge me". What's the catch - or put in a better way, what's their business model?
My guess is an eventual business model is for advertisers (the true customers) to get user information from developers who opt-in. Getting a mass-load of app developers, each with their own end users, into your ecosystem provides a lot of data to sell.