Another thought on Sketchpad: Both Sketchpad and the full Painter X need a computer to run. So there is no added convenience if you want to go outdoors and sketch. Far more convenient to just grab a paper sketch pad and a couple of pencils and go.
Also, I think you could duplicate much of the functionality of Sketchpad in Painter X. The Workspace feature allows you to hide any brushes,papers,etc that you don’t need for sketching or whatever.
Of course Painter X costs a lot more than Sketchpad, so that may be a factor for new users. But then ArtRage and others cost far less than Sketchpad and give equal or better functionality.
For current Painter X users, I don’t know that it’s that useful.
Right now, I’d say Sketchpad is mildly interesting, but not a ‘must buy’.
Maybe it’s a test for new Painter 11 features? Who knows? <shrug>