I agree that the usability is behind, as we would expect. For me mainly is about missing apps and some hardware support. But in terms of UX for example I liked using SailfishOS, although I'll admit the UI needs some getting used to.

But I prefer this to the feeling that I'm being limited on what I can do on Android/Apple, and the worry of being in a duopoly that allows the companies to worsen their products without ever fearing competition(as far as they do it in small chunks).