I appreciate apps like this as experimentation - a way to try new ideas. But this feels like a concept in search of an app.
It's a great concept for an interface. It's a beautiful interface. But as a weather app, it's less useful than the stock iOS app, and requires more taps to get the same information.
I encourage this sort of experimentation, and I hope the cost of the app funds development of further new concepts, or a more useful implementation of the concepts they have. At the very least, I hope it encourages developers of more "utilitarian" apps to step up the level of design.
I agree that a solely gesture-based app is a recipe for trouble. I've deleted both Snapseed and iPhoto for iPad because they felt like too much trouble to learn. Something like Clear or Haze is easy enough to learn and remember, because these apps basically do one thing. More complex apps need chrome on the screen, with gestures as shortcuts.