I have read the online version that "contains the complete author manuscript before final copy-editing and other quality control".
As the title goes, the book is about the basics of visualisation - "a guide to making visualizations that accurately reflect the data, tell a story, and look professional". The book is split into three parts 1) From data to visualization, 2) Principles of figure design, and 3) Miscellaneous topics. Essentially, it brings the reader from the start to the end of the process of visualisation.
The first part of the book dwells on the types of charts that can be used in different circumstances, including the pros and cons of using each frequently seen chart. Next, it goes into tips to make visualisations legible. Finally, it discusses how to tell a data story briefly.
Things I like
1. It is free. The online version is free and legally available for all to read with easy to navigate the content page to help readers move from chapters and sections quickly.
2. It is a book suitable for all visualisation tool users. Although the author uses R for the charts and graphs in this book, it does not go into the specificity of R often. Hence, readers are able to understand the content and concepts behind the visualisations easily without going into the coding concepts behind R.
3. It has pictures that help readers understand quickly. By having examples of the good, bad, and ugly charts, the author gets his point across of what to do and what pitfalls to avoid when readers create their visualisations easily.
Final Verdict: A good read for beginners who already know how to operate at least a visualisation tool.