Its definitely been a struggle for me to get my head around thingking in terms of reactive components while designing asynchronous systems till i got my hands on this book. Tomasz gets to the point right from page 1 and waste no time to delve deeper into the water to understand RXJava and its components.
Just like the Goetz (Java concurrency in practice), the language used was subtle and did not tend towards the pepper-the-pages-with-jargons kinda approach. I still have to go through the entire book but just from the initial lessons i could get a good grasp of the techniques and the particular thinking involved in decomposing tasks in terms of RX components. As an android developer I needed this badly and the book was worth every penny spent.
My search for a good RxJava ended here. Its been several months that I am used to Rx. Though I get through I often find myself uncomfortable if I am doing the right thing or not. Fortunately, this book came along at the right time. Though it covers 1.x it is very recently published (Nov 2016). Tomasz is an excellent author.