There's something really important to understand when evaluating non-fiction books: nobody reads the later chapters, and the authors generally know this. They can present tremendously one-sided information in the first few chapters, giving the spin that they want, and then in later chapters give a more balanced approach to shield themselves from criticism. Almost everyone who reads the book will read only the spin, but any criticism levied against the author will be met with "but I specifically say, in the later chapters ...". It's a slimy technique that you start to see everywhere once you're aware of it.