The first thing I noticed about this book was the weight. Think a heavy tome- not a book to read on the bus! As an aside, I would advise spending the little extra and getting the hardback because thus you can open the pages without worrying about damaging the spine. But I digress.
The book spans Art from early man to the present day, thus giving a broad overview of the trends and main occurrences. The text, while I have just flicked through it, is lucid and doesn't expect the reader to know everything, so it is a good introduction to the History of Art. Nevertheless, as some reviewers have noted, this can be a downfall in itself- it cannot go into as much detail as specific books can. It depends on what you want; as a reference book it is fantastic, with stunning illustrations. You can spend ages dipping into it, just looking at the photos and diagrams.
Particularly interesting, were the 'In Context', 'Sources and Documents' and 'Concept' boxes. These succinctly flesh out the reader's understanding of a particular period e.g. when talking about art in the Americas, there is a page on the Religion and Society in Ancient Peru. Often the context of a piece gives a better insight into it, so the book does score on that. The sources and documents range from Vitruvius's writings on Roman painting to Veronese's Interrogation by the Inquisition and thus give the reader a flavour of what contempory people wrote or did; while the Concept boxes help to explain key terms and ideas, such as 'Art for Art's Sake' and 'Modernism and Formalism.' I also liked that the book went right up to the present day (the edition I have was revised in 2009) so has current ideas and concepts in art; it is well worth getting the most recent edition as they do update the text.
Overall, it is a broad yet lucid insight into the global History of Art and it will take a long time to devour it, but it is well-worth it.