I quickly browsed through the book . In 88 pages, the book is what you would need to get started with tmux.
If you are like me, lazy (very lazy at having custom configurations for your shell/editor/whatever), Chapter 1 should be the absolute must read. It teaches the basics – creating multiple sessions, windows, panes and navigating around with them. Basics of naming sessions/windows/attaching/reattaching is shown. This chapter itself should get you quite happy about not managing multiple tabs/windows and seeing multiple panes in one window.
Once you are through with that, Chapters 2 & 3 will be your favorites if you don’t mind spending time to customize/script things up.
Chapter 4 was my second favorite chapter in the book, since it talks about scrolling/copy/pasting text from windows/panes.
Chapter 5 talks about pair programming, something which I gleefully skipped during my current reading.
The last chapter, Chapter 6 furthers on Chapters 2 & 3 about various customizations and launching tmux automatically, etc.
Each of the chapters end with a review of the most important commands/keybindings which is really good for composting your own cheatsheet. I created by own out of a fork here .
All in all, get the book if you are interested in tmux (or want to get started with a terminal multiplexer). Great job by the author, Brian P. Hogan.