This is a good book about a fascinating story. In a nutshell it is the story of Billy Beane and how he defied conventional baseball wisdom. Billy Beane was (is) the general manager of the Oakland As, a relatively poor, small market team attempting to complete with the big boys (the New York Yankees) with only a small fraction of the budget.
How could he compete? His approach was to eschew the conventional view of what a good baseball prospect is and to use the statistical methods developed by Bill James et al to help him get good players at a reasonable price. The story is made more poignant because Billy was a 'great' prospect' who only managed a fairly mediocre career - essentially his method means that he is only interested in players who are not like him. For example: he favoured college players over high school players (for one thing they have played for longer so there are more statistics, for another they are statistically more likely to succeed); he believed that on-base percentage was the fundamental baseball percentage and was not something that could be easily taught. Finally he had the nerve to put it into practice.
The style of the book is highly anecdotal, which works well most of the time, particularly in the chapters about the unlikely success of certain players, but it does occasionally grate. Unlike some of the other reviewers, I think that he includes just about the right amount of statistical detail - enough to be interesting; not so much as to become tedious.
In many ways the most interesting thing about the book is the reaction from the Club (as he calls the collection of baseball 'insiders') - who seem to a) not really understand the book and b) hate it because they are the custodians of conventional wisdom.
Highly recommended for baseball enthusiasts and sports fans in general