I can give my opinion of the book in one word, Yes! The book, The Power of No: Because One Little Word Can Bring Health, Abundance, and Happiness written by James Altucher and his wife, Claudia Azula Altucher, is about how people are reluctant to use the word "No" and if they did more often, their lives would be much happier.
You may know of James Altucher as the founder of Stockpickr, the publisher of Altucher Confidential blog, and the author of many books. However, this book is quite a bit different from all his other books.
James and Claudio draw from their real life experiences, explaining how when they didn't say "No," their lives took a turn for the worse, sometimes much worse. When they finally incorporated the word into their vocabulary for uncomfortable situations, their lives changed for the better.
Do you have trouble saying "No"? If so, read The Power of No. It could change your life.