Do you generally trust the reviewers of books on Amazon.com (especially textbooks)? Of course, it's very easy to see which reviewers are submitting poor reviews (hence providing a buffer against being influenced too much by such reviews). But on a side note - I have to note that a lot of the interviewers seem interesting. Some of them mention their educational backgrounds and the contexts that brought them upon such books. The Amazon.com reviews also remind me that self-motivated learners who read books independently of their classes are not extremely uncommon (as anyone who would come to my old grade school would ascertain - or even most people at my old university). Some of them even read textbooks on subjects as abstruse as general relativity - years after leaving academia.