You, I, and ReactiveUI (color, hardcover)

This book will teach you how to exploit ReactiveUI -- a .NET, MVVM framework that is truly unique -- to develop user interfaces for a vast array of modern platforms. The development of UI is particularly amenable to the reactive paradigm, and ReactiveUI's raison d'etre is to make it simpler for us to do so. Within, you'll experience a whole new way of solving complex software problems; ways of attaining the compelling experience we all strive to deliver to our users. Techniques for modeling complex, asynchronous systems. Succinct expression of data and its derivation. Ways to exhaustively test reactive systems. All this and much more, without ceding code maintainability.

NOTE: you can also buy this book in grayscale here. See below.