This was a very positive and engaging read that made me consider how to do more in my life for the betterment of the world. This book's title (and message) is not entirely clear until you read it. The book is not about simply doing the most good that You-the-Reader can do, although I am sure it is a play on words, but is about "what" one chooses to do, as rated by effectiveness.
Singer describes a group of people who have chosen to be called "effective altruists" and breaks this down: the definition, history, goals, motives and real world examples for such a group. He also walks the reader through some theoretical exercises for assigning value to various actions for the purpose of comparason, but is careful to disclose the complexity of many factors involved. The reader is left to make conclusions on their own, but is given a lot to think about.
For personality types such as mine (INTJ Meyers Briggs) showing me a framework for this type of reasonable decision making regarding giving is truly exciting. It engages my desire to give, and to give to actually make the most difference for others.
In the end, I did not come away from this book ripping out my checkbook, frothing at the mouth to give to charity, but I will think about this book for a long time to come and I sincerely hope that it has long term effects on my actions. I read a library copy of this book, but have just bought this book to give as a gift to others.