The most useful book for beginning players ever written. After introducing the basic principles of opening play, the reader is shown practical sure-win strategies that he or she can use in handicap games. A chapter is devoted to tesujis (tactical brilliancies), with 69 examples and 50 problems. The book ends with a chapter on the endgame.
I learned Go from this book; I can't guarantee that it's the absolute best introductory text, but it's definitely very good, and I'm one of many people who think highly of it. The authors, top Japanese players, walk you through the basic principles of the game. They introduce you to opening theory, both joseki (set patterns in one corner) and fuseki (opening play over the whole board). Since it's a beginner's text, they stress handicap openings - unlike chess, Go has a sensible handicapping system, where the weaker player is given extra stones at the start of the game. Later, there are chapters on tesuji (roughly, combinations) and life-and-death problems.
I particularly liked the chapter on yose (endings). Go endings are both like and unlike chess endings. They are like in that they are basically mathematical, and it's possible to calculate exactly a long way ahead, but the details are completely different. Just as in chess, if you have a decent knowledge of the ending you can often save apparently hopeless positions.
In my humble opinion, Go is the most subtle of the mind sports, far exceeding chess and bridge. It's just a shame that people in the West still haven't quite discovered it. Haruyama and Nagahara's book is a great way to start exploring this new universe.