Before we talk about who should read this book, we should ask who are the people that usually do Android system programming in the real world? There are potentially quite a lot. Here, I can give a few general categories. Firstly, there are a large number of engineers at Google working on the Android system itself, since Android is a product from Google. Google usually work with silicon vendors to enable Android on various hardware platforms.
There are many engineers at silicon chip companies, such as Qualcomm, MTK, or Intel to enable Android on their platform. They develop HAL layer components or device drivers to enable hardware platforms. The hardware platforms are usually called reference platforms, which are provided to OEM/ODM to build the actual products. Then, the engineers at OEM/ODM companies usually customize the reference platform hardware and software to add unique features to their products. All these engineers form the major groups working on system-level programming. Thus, if you are working in any of these areas, you may want to read this book.
Besides the previously mentioned categories, it is also possible that you are a developer working for an embedded system company. You may work on projects such as embedded system for automobile, video surveillance, or smart home. Many of these systems use Android nowadays. One of the fastest growing areas in embedded systems is Internet of Things (IoT) devices. Google announced Brillo as the operating system for IoT devices. Brillo is a simplified embedded operating system based on Android. The source code of Brillo is also included in the AOSP. This book is also relevant to people who use Brillo.
For Android application developers, system-level knowledge can help you to resolve complex issues as well. If you are working on projects that involve new hardware features, you may want to extend your knowledge to the system level.
This book is also useful for people teaching Android system programming or embedded system programming. There is plenty of source code in this book that can be used to form your own lesson plans.