I started with Sonar 6, and loved it.
When I updated to X1 I was initially confused, but, with the help of Scott's book, realised just how good the new interface was.
I couldn't imagine going back to the old one.
By the time X1d had been released, I loved the stability and workflow. When X2 came out, I was unsure if the upgrade was worth it. To my surprise, it was a huge improvement to workflow - just refining the X series.
X3 has been the same, for me. It is just getting better and better.
As with the review, 9/10 from me.
I would give it 10/10, but it still needs my input to make music..