I bought this book on Saturday. It's Monday now and I've just finished it, which for me is very fast indeed, and a reflection on what a fascinating and well written book it is.
I heard the author talking about his travels and studies on BBC Radio 4 and thought his ideas about linguistics were interesting, but when I had a quick look at the book before I bought it I realised it was much more than an work about the theory of language. It's actually a rare combination of exciting adventure story, anthropology AND linguistics. The conclusions Everett reaches after 30 years of living amongst the Piraha people get right to the heart of what makes us who we are as human beings, and provide a fascinating insight into another way of life we would otherwise never have heard of, or at least would understand only superficially.
The first half of the book focuses on the lives of the Piraha (and the experiences of Everett living with them), the second half focuses on the linguistics. This structure works really well and the book is a great fusion of entertainment and information throughout.