I started with the same simple app I used last time and then switched to Autodesk Sketchbook which is much more powerful and feature-rich. While screen size and stylus precision remain natural limitations of this medium, now I feel like it's my own skill (or more correctly lack of it) that restricts me, far from being capped by application possibilities. Fun.
There was another person with a tablet in the class today - first I though that was iPad, but the screen was even bigger. When I took a closer look later it turned out to be a tablet PC running ordinary Windows and Photoshop. Apparently it was also pressure-sensitive making it an ultimate drawing machine.