This at once absolutely wrong....and yet, I can see where he's coming from. All in all, I just use the included Preview.app (for quick cropping, etc.), iPhoto, or GIMP.
Paintbrush is available as a free download and is everything you’d expect from an MS Paint clone. It loads incredibly fast, can open almost any type of image, and lets you edit and paint images quickly and easily. Paintbrush fills the void Apple created when they removed MacPaint from the OS.