It is a shame more people haven't read/reviewed this book since it is so easy to read and can help a motivated person understand how to improve their day to day happiness with some simple techniques. I suppose you could select a more academic approach to understanding cognitive theory, but why? Actually, if even Daniel Kahneman, winner of the Nobel Prize in Economics, keeps his groundbreaking tour of the mind in "Thinking Fast and Slow" as simple as the authors of "Engineering Happiness", then the key to appreciating the book is its simplicity.
The first discussion of the "Laws Of Happiness" reveals social comparisons the brain automatically makes, such as what we have vs. our peers. From how much you earn, to what kind of car you drive to the test results you received in school, your brain makes comparisons and your happiness is fundamentally based on these comparisons. For instance, back in your school days, chances are you were really happy to get a B in Statistics until you found out all your friends received an A. You were immediately, and negatively, impacted by the news of your peers grades and that good feeling you experienced was consigned to the rubbish bin. But should you have done that? Of course not!
The Laws of Happiness presented in the book around satiation, expectations and framing are simple to understand, share with others and use every day. It is important to understand how you think about happiness, especially if you want to improve how happy you feel. I was initially curious about the book and I couldn't help thinking about disappointments in the past, some quite recent, and how unhappy they made me feel. Understanding the role of "basic" goods in my happiness and the rules of satiation gave me a new perspective on how to go about every day in a new way.
The aforementioned book, "Thinking Fast and Slow" is equally accessible and is a much more detailed description of cognitive theory, but still very practical. I read it after "Engineering Happiness" and it made me even more appreciative of the authors "Laws of Happiness" approach.
If you want another interesting insight into how our brains affect our perspectives, happiness and how it manages complexity, read "The Black Swan" by Nichalos Taleb. Review his theory on our propensity for simplistic reductions of the complex events we experience. His ideas on how we think influenced Kahneman ["Fast and Slow"], and I found these books to be formative, helpful and well worth the investment of time. So get happy ;-)