I recently bought a Wacom Graphire4 tablet. When I used it on Paint.NET, using the Paintbrush tool, when I pressed harder, it made a thicker line, and when I pressed softer, it made a thinner line. It's not that this is a bad thing, but sometimes it drives me crazy. This is what I suggest:
Good: The ability to switch this off.
Better: The ability to switch between thickness, nothing, and alpha.