He's pretty serious in what he does and is more known for his room treatment products and advice. Has the appearance (at least to me) of a basement guru, that is having some success, thanks to the internet, and able to expand on his original goals. It appears he isn't getting rich, but is making a living doing what he likes and believes in. That IS the definition of success in my opinion. I've never heard any top notch recorded music mixed, created or finished by him, although he plays a bit of cello and other instruments, like a jack of all trades, quality. His equipment he uses seems to be middle of the road as well. He does have a presence on the internet which you'll see on all the acoustic type forums. Check his website and the variety of videos he's made. I don't disagree with much that he states, and he'll make some bold statements now and then, but he's seemed to have found a niche and is doing well by it.
Ought to be a good value in getting his book, although I haven't read it. As far as geared towards *truely advanced*, I might tend to slightly disagree as a GUESS. But it should have lots of good info, never the less.