And yet Sailfish is a mature mobile OS, sufficient in many cases to be a daily driver, and an essential EU-based alternative to the Apple/Google monopoly. So there's that...

On a more superficial front, the UI is far ahead of both iOS and Android. Complaining about it being closed-source misses the point: the platform is Linux, and other than the proprietary front-end, everything else in Sailfish is wide open to hacking and independent development. So there's that too...