I've had my N9 for quite a while now, and compared to my wife's Galaxy SIII, I prefer the N9's UI.
But that's because I'm used to it - just simply double tapping it to wake it up, and a swipe to do most things.
Jolla is taking some of that a step further.
The N9s multi-tasking is superb compared to most if not all phones on sale at the same time that it was released, and many released after it. It's a jewel in Nokias fallen crown, which has been replaced by monkey metal stars.
I look forward to Jolla's first phone, or the first phone to run Sailfish should I say.
As for the similarity to BB10, my opinion is that BB10 is similar to MeeGo/Mer/Nemo. And that looks good too. I hope it reverses their fortunes.