This is definitely a very comprehensive book on how to be a good Java architect in general. It has a lot of background information, which helps to put everything you learn in the right context. It is therefore especially useful for beginners in this area.
If you are an experienced architect, who wants to quickly review all exam topics, you might be a little disappointed though when reading the chapters. It has so much background information, that the book isn't always to-the-point. Although each chapter does end with a 'two-minute drill', which should make you aware of all critical information covered in the chapter.
Overall this book is still the one-stop for exam preparation that most people are looking for, with all the exercises and the case study. So it's worth the money when you're thinking about taking the Java Architect Exam.