Their category stack - ranks work well for authors who publish a lot. (madgeniusclub.com)
It's important for authors of all stripes to know as much as they can about the tools they have available to them. (lulu.com)
So it's good for the books that are in that program, but it's not good for authors who are trying to earn a living, selling stand alone copies. (thecreativepenn.com)