When you think of Escher's art, you're probably used to seeing the end results - his impossible worlds (High and Low), or the complex chains of tilings (Metamorphosis), rather than the basic simple tilings which form the core of so many of his works. That is what this book is about.
Effectively, this book is an annotated version of the notebooks Escher kept, full of ideas to make finished pieces with. There's some discussion of how Escher classified the kinds of tilings, and how this fitted with the approach of crystallographers and mathematicians, but it feels a little woolly, although I'll happily admit it's probably beause I only skimmed that part... this is not the kind of book with proofs.
The core of this book is the designs and they are, indeed, wonderful. You can see the development of his styles and interests, and how these works fit with his finished pieces. However, I also found it very interesting to learn a little more about Escher's background - to learn that while he lived through the Nazi occupation his Jewish mentor was taken away, to find he'd crossed paths with Polyá and Penrose, and to see his inspiration by the Alhambra. As his design work is so abstract and detached in many ways, it's odd to find out more of him as a concrete human being!
Finally, this is another book from my backlog of doom! I bought this in 2004, during a trip to the Edinburgh festival with Caroline, our very first holiday together. I doubt I'd have believed that we'd be married before I'd read this book! So, it's not only an enjoyable book, but a rather lovely reminder of those times.