Michel Foucault is a great philosopher, but his interpretation of Rene Magritte's works, most specifically, 'This is not a pipe.' is not for the beginning reader.
The only way to really sum up what this book is about is one word: treacle. For the philosopher or the art afficiando, this book is a godsend. He gives you everything you could possibly want to know; his essays incorporate others' works as well, and all of the pictures are nicely arranged in the back.
However, for those looking for a quick read, something that caught their eye, or are fans of Margitte, don't buy this book. It over analyzes the artwork, and thus ruins a brilliant piece of art by delivering a mollycoddled interpretation.
Just my opinion, hope I can be of some help.