It begins so good in the first few pages, but ends up pretty flat as it mixes up common sense with rational thinking and critical thinking. It is the "critical" prefix that should be the important differentiation, but here he makes the "thinking" part the important thing. If it kept at the critical thinking part, and went from there it could have been something, but it is too simple and too "follow these steps to become a better critical thinker", and then uses so many pages to tell us why critical thinking is important in different vocations.
It's not a total waste, but this is not the book you want on critical thinking.