I started using this new app from Autodesk last week and got hooked since. Would it replace my favorite Brushes app for my Itouch paintings? Not yet. I still like the speed and very intuitive interface of Brushes. Sketchbook Mobile though has opened a whole new array of customizable tools that made me too excited and overlooked the slow responsiveness of the sliders. But after getting used to its interface, the slowness starts to bug me. Guess I need to be patient - for the price of $3, can't complain (Brushes is not bad too for its $5 tag). Anyway both these apps come in very handy when I have an itch to draw or paint anywhere, any time. Can't express more how useful sketching/painting on iTouch for me (still using my good old pointer finger) in thumb-nailing designs at the studio.
Next task: combining Brushes and Sketchbook Mobile apps cocktailed with PS Mobile. Stay tuned.