This is a difficult book to review objectively - like alot of self help books, whether or not the reader will find it helpful is completely subjective.
As obectively as I can be - this ebook is formatted well and was very easy to read. I read it cover to cover in about an hour and 1/2 so if you want either a "quick read" rather than anything too deep and meaningful, this one is good. If you have read quite alot on the subject already, this book may also be useful to act as a reminder of some of the basic principles of finding happiness. Each of the 18 rules are discussed in individual chapters making it easy to refer back to paricular points at a later date if you want to.
The down side is that each subject is not discussed in any detail and whilst the author does give suggestions on things you can actually do to find happiness - go out with friends more often, take up a new hobby etc.. the book doesn't acknowledge such changes are not always that easy to do. The author also fails to discuss the changes in perception the reader needs to make both of self and the world around them in order to put each rule into practice in the first place. He does say throughout the book that we need to change how we think about things but does not discuss "how" to change our thinking
In summary, this book gives the reader advice on practical changes he/she can make in their lives to help find happiness rather than focussing solely on changing thinking, perceptions etc.... Personally, I did not find it helpful as it only covered the practical changes you can make and did not really cover the psychological. However, if you have read books about "positive thinking" and want something to help put that into practice, this book has some good ideas. If you need help with how to change your thinking in the first place, this book may not be much help as it only acknowledges you need to but doesn't give any help on how .