I haven't read it but from what I hear the overall concept is:
If a guy isn't calling you, is cancelling plans, is acting disinterested, is sleeping with other women... it doesn't mean that he's "complicated" or "very busy with work" or "afraid of commitment" or "intimidated by you".
It just means that he just isn't that into you. so why are you wasting your time stressing over it?
I guess it makes sense and is empowering to women because they stop wasting their time in dead-end relationships (that really aren't "relationships" at all, but they were otherwise too blind to see that). Basically it keeps women from embarrassing themselves by continuing to pursue a man who isn't interested and it keeps women from having nervous breakdowns when they finally realize that a guy they're dating doesn't want anything to do with them.
But mostly I think it's a little overly simplistic.
I don't see it as much of a threat to DJs because I think it doesn't really address men who are just acting "aloof" but rather men who really AREN'T that into the woman. (Truth is, if you AREN'T into her, then you wouldn't care anyway if she stop bothering you).