We have had these apps in various EU countries for quite a while and it's been fine. You can get a prepaid SIM from a grocery store and register it with them, and so on. You can always SEPA transfer the money if you don't want to use this.

It's also more convenient than giving out an opaque UUID to your friend to transfer you money or something similar.

The bigger problem I see with this is it being one more service locked exclusively to Android and iOS devices, but it's the same with most currently used banking apps anyways.