I can say this already, without having received it yet:
It's gotta be good because all his stuff is good. Read the descriptions of his other materials. His decsriptions, IMO, can serve as reviews.
The best way I can think of to review it is to compare it to his other materials and to say if it really does help with the rock genre in general. I'll do that after I've had the chance to assess it.
Rock is such a very diverse genre. It's hard to imagine this book being very comprehensive to rock, but maybe it will lay a foundation that will underlay many forms of rock. We'll see.
If nothing else, it will contain exersises and theory. I'm sure these exercises and theory are covered in his other material, but if you don't have his other material and are interested in rock, this book is sure to be a good purchase.
I'll have it in my hands soon. I'll keep you posted.