A UX colleague of mine initially recommended this book to me, and I started leafing through it. And when I looked up again, I had read half of the 125 snippets that make up this book...
This is the strength of this book - instead of taking one theory and squeezing 300 pages out of it (as so many other design and UX books do), it deliberately dedicates exactly 2 pages for each theory. The left side of this bigger-than-A4 book is dedicated towards theory, with very handy references of where one can find out more about the theory, while the right side has good visual examples of how this theory maps out in the real world.
For a seasoned professional, many of the theories will be well-known, but I was still surprised by the often clever cross-referencing to other pieces of research that made me think anew about the theory. Also, the authors made a fantastic effort in boiling down often very wordy theories into a few very concise paragraphs.
I also really liked the mix of theories: there is a lot of design, a lot of psychology, evolutionary biology, Gestalt and other research on perception, motivators, and many other things... this is a strength of this book because everybody who reads it will find something new from a related discipline, and the book makes it obvious why this is still relevant.
I thoroughly enjoyed reading it, also because it's easy to just pick it up, read a couple of theories and put it back down. I recommend it very much for people who always wondered what some of the names of the theories were that they were using on a daily basis, but also for students of design and UX who want to "cheat" and get really handy quick explanations of complicated subject matters without having to fight their way through the often tedious books of these areas.