I remember when this used to be an Alias product that was developed mainly for industrial designers and car designers. It's had a completely different development history than a product like Photoshop, and has always focused on the drawing/painting experience.
SketchBook Pro features drawing tools that concentrate on trying to emulate the feel of pencil, pen, marker and airbrush on paper, and does one of the best jobs in the industry at providing precision and accurate sampling input from a pen or stylus. The product includes basic masking tools as well as some geometric drawing tools, layers, and more.
The interface is very straightforward and is essentially identical to the iPad version and slightly cut from the desktop version.
The feel of Sketchbook Pro is much like you'd find on the iPad however be aware that if you have too many applications running in the background that are resource-intensive or there are any updates or downloads happening in the background, you will experience the occasional lag or incomplete line!
However, once your downloads/installs/notification-heavy apps have stopped interrogating the OS, you'll find moments of lucid drawing that, aside from the slightly slippery aspect of drawing on glass, will feel amazingly fluid and realistic.
One major feature I'd like to see added is the ability to save custom brushes and although I haven't tried it with a keyboard yet, I hope to be able to control (e.g., change brushes, brush sizes, tools, etc.) with keyboard commands. I'll report back when I get my keyboard.
For the sketcher in you, this is an excellent and responsive tool and a must-have.
