Funny thing is: I haven't even read the book yet. But the thought is so simple it really doesn't require much more elaboration. But if you need one, I think this line from the web site captures the essence:
Inherently, we all know that an image isn’t measured by its resolution, dynamic range, or anything technical about cameras or photos. An image is measured by the simple — sometimes profound, other times absurd or humorous or whimsical — effect that it can have upon us. If you can see an image, it can move you.
Which is more than what I can say for all the fetishism around DSLRs. Really, people, what are you trying to compensate for?