Having not read it myself i cant say for sure, but it seems to me reading review of it that it is more about the brain being able to learn at a later age rather than some in depth teaching aid. this is what one reviewer had to say about it.
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I never felt like we got settled down into a flow because Marcus spends so much time touching on so many different subjects all the time.

Neurological science, music's historical and cultural origins, interviews with famous guitarists, anecdotes of famous guitarists, talking a lot about how precise a musician's movements have to be, responding a lot (directly and indirectly) to the claims made in Malcom Gladwell's "Outliers' (which, coincidentally, was the book I'd finished reading right before starting this one; how about THAT!), and a little bit about his journey into music.

Interestingly enough, the thing he focuses the least on is what I expected the book to be about: him learning guitar. He abandoned that pretty early on, it seems. He did spend a whole chapter talking about his experience at a youth Rock and Roll Camp, but there wasn't much personal stuff after that. By the end of it, I'd read a lot of interesting stuff, but I didn't walk away feeling like I'd been on a journey or anything--that lacking feeling was punctuated by the way he talked about his next musical ventures, such as with the MIDI guitar . . . it's like he headed off to 2nd grade one morning and the next time I see him, thinking it's the next day, he's graduating high school.

There's a lot of stuff missing there that I wanted to hear: his struggles with grasping more advanced music theory, his personal guitar lessons, his practice schedule, the things he focused on to learn and build his repertoire, other stage experiences (I felt he implied he had them), and instead I got to hear a lot about gray matter and the creative genius of Bob Dylan.
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Doesn't sound much like a teach me to play guitar book to me..

He's hardly Russ shipton is he. lol.....