This is a well-written, well-researched, and incredibly important book. I think that people who aren't in the mental health field could probably read it without realizing how important it is, in part because Watters does a good job of being objective and giving his subjects the benefit of the doubt - i.e. he assumes whenever possible that the mistakes being made are being done with good intentions. Towards the end of the book he reveals that his wife is a psychologist, and implies that this helped guide his perspective on this matter.
But the book is pretty groundbreaking in some important ways. It challenges a lot of the fundamental ideas about mental health and makes a good case for the idea that what we think of as fundamental ideas about psychology and health are in fact products of American civilization. Which would be fine, perhaps, if we were only using these ideas to heal ourselves, but we're not. We're assuming those ideas are what's right for everybody, much as we do for our ideas about what form of government everyone should have and what values people should hold. He doesn't really go there and say this explicitly, that's my extrapolation. Like I said, Watters is actually quite understated in his writing - he assumes even in the case of pharmaceutical companies marketing antidepressants in Japan (changing the fundamental cultural definition of depression to do so) that for the most part, people at these companies are doing so with good intentions.
All mental health therapists and psychiatrists should be required to read this book.