This book is worth reading even if you do not agree with its conclusion.
The book consists of demonstrating a number of logical flaws prevelent in human thought. Not all of the 'flaws' are demonstrated as being true and the opinions of the author, although proporting to be rational, often fall foul of the very flaws he has just demonstrated. For this reason the book provides a cautionary tale of just how sneaky and prevalent irrational thinking is. The central flaw is that the author has obviously made up his mind as to the correctness of his opinion and consistantly fails to take into account alternative or unsuporting evidence. Do not expect a pros and cons argument as to whether or not a particular example is rational or irrational - even though he recommends the pros and cons method as one of the best ways to determine such things. He also falls victim to the halo effect - decribing "The Great Randi" as "the world's leading magician" (p228) is an easy example. The examples given in the book also unintentionally demonstate the "availability error" on numerous occasions.
However, although many of his examples are flawed - the explaination of the availablity error , halo effect, tendency to only look for supporting evidence is generally good and well worth knowing. He is particulary good at bringing attention to errors in the use of mathematical probabilty - many of which can have a significant detrimental effect on medicine and justice - for example he proves how a lie detector test with a 90% accuracy on a question can be far more likely to give a false positive than a true positive if the test subject comes from a largely honest (for that question) population. Such errors are worth knowing about and taking the time to understand.
The tone of the author can sometimes be intellectually elitist - more so than say Richard Dawkins. Many of the examples used can be seen to be political - in general the political examples tend to lean to the left in the first part of the book and to the right in the second part of the book - This is evidence of independent political thought.
It is in the chilling nature of it's conclusion that I most disagree with this book. Even though he tries to mitigate it's nature with disclaimers, the idea of the Unitisation of human life and abilities in order to make 'optimally rational' decisions carries with it a degrading effect on the value of people as human beings. This degrading effect is probably far more evident today than in 1992 when the book was first published.
Overall this is a book well worth reading especially if, as the author points out, it will challenge your existing opinion. For the science however Predictably Irrational: The Hidden Forces That Shape Our Decisions
is a far clearer and easier to understand book without the polemic and elitism although it does not cover every irrational error this book succesfully exposes or attempts to demonstrate.