I really wish them success, but I just can't see it anymore. I had the first version and it seems it didn't move much forward from that time. And there were also many screwups, as poisonborz reminded a bit earlier.
Their UI looked novel, but wasn't that great in practice. It wasn't stable (hopefully that changed) and the lack of real apps was killing it before and now even more, as more banks/govs require some "trusted" apps
I dispute your assertion: Sailfish's UI is WAY ahead of iOS and Android. It's simple, consistent, and intuitive; a complete contrast to the mess of iOS and the clunkiness of Android. As for stability, native Sailfish apps on my Xperia XA2 seldom, if ever, crash.
And, to my eyes, it simply looks better.
I had Sailfish on XPERIA and it was no less stable than Android/iOS in my experience. But that wasn't the first version I don't think.