The Unix-Haters Handbook is a book written by a group of people who don't like Unix (a type of computer operating system). Imagine if you were playing a game and you really didn't like the rules, so you decided to write a book about why the game stinks.
In this book, the authors talk about all the things they don't like about Unix, and why they think it is a bad operating system. They use funny pictures and jokes to make it more entertaining to read.
Some of the things they don't like about Unix include how difficult it can be to use, how there are too many different versions of it, and how it doesn't always work well with other programs.
Even though the book was written a long time ago, it is still talked about because it is a funny way to learn about the history of computer operating systems. Some people think it is still relevant today because there are still debates about which operating system is the best.