Now I've read two books about the history of Google: The Google Story and John Batelle's The Search. Of the two, I recommend The Google Story. It picks up on some things which Batelle overlooked. When you read that previous sentence, you might think Oh no, I don't know if I want that detailed a history of Google. But it's not that this book is longer, more that its analysis seems better.
(My opinions are mine; they're not necessarily my employers'.)