Very interesting, clearly written information to enable you, the poker player, to make better judgements at the table based on what other players are doing, not saying.
Decide if a player is bluffing, or has a strong hand just by studying their movements, feet and facial expressions.
The writing style is easy to follow, its extremely readable, and the black and white photographs are clear and very useful in illustrating the various tells Joe Navarro is explaining.
Obviously, this book is not much use for online play, but for live play, its a great introduction to the world of tells and making money from other players unconscious actions at the table.
Only slight criticism is the inferior quality paper used in the printing of the book, but the content is pure gold.