As usual, Prof. Kagan is interesting and provocative. But also way overstated, such as the cover blurb claim that he succeeds at "revealing the bankruptcy of contemporary questionnaire-based personality theory" !! His own work (see Galen's Prophecy) on the temperament of behavioral inhibition is in fact remarkably consistent with "contemporary questionnaire-based personality" research on shyness and inhibition. Most well known psychologists have some extreme hobby horse they can't resist riding, and questionnaires are his. Evidence of multi-method triangulation of findings is ideed crucual, but picking on one method over others is ultimately silly. Still, it is interesting to keep up with his books.