The negative reviews of the book are mostly from people who never read past the title.
I was treated by Dr. Saul in the mid 80's, before ADD/ADHD were even a diagnosis. He helped me then, and he continues helping people today.
The unfortunate truth is that the term ADHD has become so generic, and so commercialized, that an entire industry of pill-pushing doctors has grown up around it, well funded by the pharmaceutical industry.
"ADHD" is a catch-all term, like "headache." In much the same way, it covers a lot of symptoms with a lot of potential causes. There are different types of headaches, with different causes, and different solutions. Migraines, tension headaches, eye-strain headaches, headaches from congestion, lack of sleep, high blood pressure... ADHD is similar in that there are different factors, and different solutions. ADHD can be caused or aggravated by all sorts of things - medicines, sleep habits, stress, anxiety, neurological issues or injuries, neurotransmitter imbalances, and myriad other contributing factors.
Dr. Saul has never told anyone that their symptoms don't exist, or that they're 'just imagining it.' Instead, he tries to find the actual causes and contributing factors, instead of merely saying "oh it's ADHD" and throwing amphetamines at you or your child.