Honestly there isn't much to say about this book. If you have ever wondered what happened to art after "modernism," this is the book to read. It's a must for any contemporary artist--contemporary as in present, not in the art sense, which would cut off around Warhol. This book can also be used to prove to anyone who thinks art doesn't require thinking that it requires quite a bit more thinking than they would expect.
If you find reading a normal book challenging, this isn't the book for you. Many of the ideas will escape you unless you have a good working knowledge of the concepts behind postmodern theory, such as semiotics and psychoanalytic theory (especially Freud and Lacan). I would recommend Visual Culture: The Reader (edited by Evans and Hall) to provide a basis for this background info.