I have started reading this book in December of 2013 when it was still in progress. Probably I have stumbled upon it somewhere on GameDev.js Facebook Group but I cannot really remember how I found it, but important point is that this time I have read it from cover to cover all over again to feel the difference with finished book.
The good thing about this book is that it is available both on paper and for free if you want to read it online. Just go to http://gameprogrammingpatterns.com/.
I really liked the book and the hand drawn illustrations that really help understand the ideas. Best thing is that the author tries to emphasize how dangerous those patterns can be and many times warns the reader to do not use them if not needed. In my opinion having a list of downsides and pros of each pattern in one place that you can easily check in the browser, is really handy.
I have no idea if I am ever going to use any of them but having understanding of the underlying ideas behind for example Quadtrees can be useful if I am ever going to use it.
This book is for sure not only for game developers as many of those patterns are used in all kinds of applications. Other to be understood are coupled with descriptions of common problems, for example, how memory partitioning works or how you can implement your own language.