Why? I'd say it's pretty good, i like it more than photoshop. Why? Because i got used to Paint.net earlier than photoshop. And now i have photoshop,
i still use and like Paint.net more. Photoshop takes too long to start up, and takes too much space. Also, Paint.net is free, and there are thousands of
plugins and tutorials. Photoshop might also have much plugins, but i haven't looked into that. And, i love the interface, the color choosing window,
the possibility to anti-alias lines as you draw them (not with the penciltool, just with lines and the paintbrush. You also have the possibility to
not anti-alias the lines.