The book is interesting, as is the journey, as Dan Harris is not someone you'd typically associate with "finding" eastern religion or taking part in trendy meditation practices.
He was assigned the "religion beat" for his news agency when the religious right began to be organized enough to affect elections in the U.S., and was well placed to be prominent in the early 9-11 news stories about the Taliban. Through these religious investigations he met a large number of people who had different visions, some were charlatans, and many who truly seemed to believe what they were selling (and some who were both).
Along the way he interviewed several current-day proponents of meditation, who seemed to defy ageing and to be quite centred and happy in a stressful world, without being '60s holdovers on communes.
As Harris' life became more stressful, and he began to explore drugs to assist with the constant stress, he came close to losing it all. He reluctantly began to explore the methods that he was covering in his job and found that he was better able to handle issues (e.g."respond" not "react"). He honestly explores how this change in philosophy interacts in an industry that would typically sneer at these actions, and how his journey was not a linear success story.
What I like about the book is the understated title - "10% happier" not "This will change your life"-type hype. The title is a bit of a joke, as it was stated in that form as a humorous answer to people probing on his new perspective, though the "no preach" and "worked for me" approach is a much better sell to me than the slicker-marketed campaigns often shown.