I paid CHF 3 for the app. It was free for quite a while but at some point they started charging for it. Now granted, that was a one off purchase, but considering that most of the logic could actually be done in the app itself, and the server could be used as just a data store, I'd say these CHF 3 would go quite a long way in paying for that.
Actually, most of the logic is done in the server. They're running some fairly sophisticated machine learning code that's beyond the capability of an iPhone. (It's pretty hard to distinguish between brisk walking, cycling, and driving in slow traffic.)
