As stated it is only for Apple users which is a bit irritating as they usually are not aware enough of topics like privacy (which can be seen by which devices they choose).
Second it is not open source and they use “straw man arguments” to deal with this problems. That’s not trustwhorthy that’s hypocritical.
And finally: Tales from Paulaner Garten, as we Germans say. So they claim alot but it is not really verifiable without considerable effort.