This brief book gives a very concise introduction to Advaita Vedanta, a "non-duality" school of Vedanta, which is apparently one of six schools of Hindu philosophy. The strength of the book is also its weakness. It is good for people who want a quick, simple overview of this school of thought/belief. It could almost be called the "Cliff's Notes" of Advaita, or even "Enlightenment Lite" for those in a hurry. Its weakness is its superficiality, as I found it very unconvincing, and in the end, just another belief system.
The book repeatedly emphasizes that the truth is beyond the ability of the mind to grasp (which may in fact be true), but then it jumps to its rather dogmatic conclusion that all of reality is only presence/awareness and the entire universe of physical objects, persons, and events is pure illusion, just appearance. Presto! Since you and I don't exist, and everything is an illusion, there's no such thing as birth, death, good, evil, and meaning. Everything is a "dream" of pure Awareness. Don't seek enlightenment; you're already enlightened! In fact, you are inseparable from pure Being/Awareness. Just leave the mind behind and let the illusions drop. (Easier said than done.)
Although presented in a very helpful and sympathetic manner, the exposition seemed sloppy to me, and in the end it just became another faith/belief system. Of course, to the truly enlightened, they know better. There is an odd mix of humility and smugness/spiritual superiority that is common in books like this.
But it's a short book and worth reading to get the philosophical gist, even though you probably won't come away convinced that it portrays ultimate reality.