A lot of people here really like the book, and Its still fairly relevant. It has some problems though, especially considering her glossing over of the events of September 1914, which I would argue is the most important month of the war. A book I would recommend would be The Marne 1914 by Holger Herwig, which was published in 2011 (the newer the better). Herwig is a German specialist who provides a technical description of the Invasion of France and the Marne offensive. He provides a great description of the Campaign, the Battle of the Marne, and the reason for the German failure.

And that is one key difference between Tuckman and Herwig, Tuckman blames Kluck for the failure of the German offensive. But she is wrong. And Herwig explains why.