I think people are able to get the same sort of value out of this book like with any other book in a given field not written by a professional in that field. That is to say, "it varies". Some like it. Others don't. We've had people in here promoting it - and in the interest of balance and all that, I think it's good we see a post like this one here also. I guess it's a matter of whether you can find yourself in what you're engaged with, or not.