Haidt gives an incredible overview of both ancient theories and modern science, to provide the reader insight into why they think the way they do, and how to make practical, day-to-day changes to their life in pursuit of happiness.
Unlike some modern self-improvement or business literature, the book is not filled with 100 personal stories, linked together by some motherhood statements. It is detailed, incisive, makes incredibly well researched points, and does the best job I've seen of walking the line between academic and average Joe needs.
Have bought 3 extra copies to give to family and friends!