I got Sketchbook in a bonus pack with maya and decided to install it. Whoa, it is really cool. I have to say, whatever problems autodesk software has they do a really good job with their UI. I sometimes find Photoshop and Illustrator to be menu-hotkey-dropdown-clicking hell, but Sketchbook is kind of a joy to use. It's also not fulfilling exactly the same purpose but be that as it may, I really appreciate having so much available right at the pen tip. I find the layers list somewhat clunky, but other than that, it seems very nice!