As an Architect focused on the renewal of Catholic sacred architecture, I enjoyed How to Read a Church quite a bit. Author Richard Taylor presents the material well, in a readable manner, and the list of subject matter is quite thorough. Simple black and white illustrations are provided throughout the text, with several plates of gray-scale photography in the center of the book. All of the illustrations are of course an essential aspect for a work describing saints and symbols in ecclesiastical art and architecture.
The readership seems to be the real question here. The volume is perhaps small enough for a pilgrim to carry along for a journey to visit the churches of western Europe, but the impression one has is that this book is probably more applicable for the student than for the traveler.