If you want to get a fine overview of Siza's works, this book might be just fine. It inculdes a short presentation of all of his works, the major buildings are featured more extensively. There are plenty of Siza's beautiful sketches and abstract line drawings might clarify his projects sufficiently (how could the editor oversee that the faculty of Porto is mirrored?). It is remarkable that most of the photos do not present the the projects in the just finished state, but how they look like right now, making plain how gracefully Siza's buildings get older. I have to agree that Le Croquis might show his major buildings more in depth and documents far more Siza's own point of view with two long interviews, however this edition is for sure worth the money.