Yep, it works a lot better for some apps than others. To be fair, a calculator app doesn't need (as much) long term development or maintenance so I think a single payment is fine for both dev and customer there.

In light of this news, I wrote up a short post about how we made Zombies, Run! a subscriptions success:

https://medium.com/@adrianhon/how-we-made-an-app-store-subsc...