If you take Daniel Marzona's word for it, fully half of the most significant works in Conceptual Art were owned by his parents. I'm not kidding: of the 34 artists whose work forms the main body of his book, fully 17 are represented by pieces which reside in the "Staatliche Museen zu Berlin, Marzona Collection." Unfortunately, these featured projects are often not the most representative, most iconic, or most interesting of the artists' works. The resulting volume ends up being more of a vanity book for the author's family's collection, than a tight survey of the most important works in the field.
The Taschen "Basics" series in which this book arrives is an otherwise well-conceived collection of trim and helpful references, ideal for students. Each volume treats a significant art movement (Cubism, Surrealism, etc.) by presenting a sequence of "greatest hits" -- two-page spreads discussing an artist and one of his/her best-known projects. Borrowing the authority of this book series, Marzona's volume disingenuously presents his family's collection in a context which increases the works' value, at the expense of the reader's trust that this is an impartial survey of the Conceptual Art movement.
The Marzona Collection is a legitimately important collection of Conceptual Art; if you're interested in the works from that collection, get a book which doesn't pretend to be anything else, such as, well, "The Marzona Collection" available from Hatje Cantz (ISBN 978-3775710978). But if you're interested in appreciating the best works in Conceptual Art from a less biased editor, consider instead the similarly priced handbook by Paul Wood, the elegant coffee-table books by Peter Osborne or Tony Godfrey, or the more theoretical/historical treatment by Alberro & Stimson.
Just to be fair -- the author does do a thoughtful job of including excellent works by conceptual artists from diverse backgrounds, such as Ana Mendieta and Adrian Piper. Interestingly, the selected works by these artists are not in the Marzona Collection.