I saw that the day he posted it - it's my only bad review so far, anywhere.
I thought about answering it, but I figured it's really not worth the trouble - sales through Amazon have dipped slightly, but not much - they still sell about 80 copies a month or so.
I was sort of flattered that he said it's not as bad as the 'for Dummies' book. I haven't read their theory book, but all the Dummies and Idiots books I've looked at have been pretty decent in their subjects.
The other two faults he finds - that I'm not 'up to date on advances in guitar tablature' and that you need to have more than a basic undertanding of music to use the book, simply don't make sense. You can't learn theory through tab - tab does not distinguish between F# and Gb (an important difference, for theory!) or other enharmonic notes - so tab is only used to facilitate understanding the standard notation.
You don't need any background in music to use the book, either... but it won't teach you how to play guitar. If you're looking for a book to give you all the chord fingerings or scale patterns, this ain't it - there are books available for those purposes.
My impression is that here's a guy who plays some other instrument, and figured understanding theory as applied to the guitar would make him a guitarist. That's not the way it works, and it's not what the book was written for.