I have a couple ideas for the way the brush interacts with the canvas:
1) Currently, the oval that represents the brush head will be at one orientation until you start draging the tool across the canvas, then it immediately flips around to stay parallel to the direction of the stroke. It's this initial flipping action that I find hard to predict or control with precision.
I think it'd be helpful if the oval preview behaved the same when the cursor is being moved around (but NOT dragged) as when it IS being dragged. That way, the brush is always rotated to stay parallel to the direction the cursor is moving.
2) As an option, maybe the brush's shape could be "dialed" in from flat (similar to the knife tool) to oval (like it is currently) to perfectly round, and of course everywhere in between.
3) Right now, as you drag the paintbrush across the canvas, the leading edge of the paint streak is straight... leading one to believe that you could bring it right up the edge of another color and just touch it without overlapping. But then, as soon as you release pressure from the stylus.... BAM! One last messy glop of paint is put over the once nice stright edge.
It'd be helpful if at any given time, when you stop dragging the brush, the paint that's been laid down stays as is, with no new globs added as a result of ending the stroke.
Thanks for listening!