Please read the title of this book before buying this book. The title is, "Practicing the Power of Now: Essential Teachings, Meditations, and Exercises from The Power of Now"
What you should take away from this title, and what the detractors missed, is those last five words, "from The Power of Now".
What this means is, this book is a condensed extract from the original masterwork. It's also quite well done. There are some original exercises, which cut straight to the key point, which is how to achieve "presence."
Although I own the original masterwork, I refer to this book more often. It's a great workbook, lunch reader, and meditation guide.
Go ahead, read part of the book to see it's power for yourself. Search for the word "myriad", which appears on the first page of the first chapter, and read a few pages. If you like what you read, make your own decision.
P.S. Another way to appreciate the Power of Now is to listen to the audio CD or the download version from Audible.com. Well worth every penny. And don't worry-you are not about to be sucked into an expensive series of seminars or anything else-Ekhart Tolle's only products are a few books. I recommend you listen to the audio version, because as others have said, there's a very spiritual aspect to Eckhart's voice, but all you really need is the original "The Power of Now" or this book, "Practicing the Power of Now."