I find Xournal is great for doing layout roughs for comic books, and other types of notes that involve lots of doodling and writing by hand.
However, the shortcuts are very awkward. It's not really possible to do the three-key reach of CTRL+SHIFT+P and CTRL+SHIFT+E or CTRL+SHIFT+R with one hand while holding onto the Wacom stylus. I've also been spoiled by many art apps that provide for one key shortcuts, just p for pencil, b for brush, even the period and comma for zooming in and out. It would also be a big help to be able to quickly key through the eraser modes, instead of having to dive into the submenus. When you're in drawing mode, and not typing text, it seems there's no reason not to use these keys more directly in this way.