I love this book so much. It is a treasure. You can tell from the text the Remzi and Andrea are natural educators, and their sense of humor makes you want to read more.

Years ago when I used this book, I was blown away by the clarity and concision of their explanations for non-trivial technical content. In particular, their treatment of scheduling stuck out to me. To my knowledge, no other OS textbook explains scheduling in such an intuitive way -- the typical treatment is more like "meh, here's the zoo of scheduling algorithms". In this book, they start with a long list of workload assumptions, and discuss the optimal scheduling policies under these assumptions. As they relax assumptions, the optimal scheduling policy changes.

Also, OSTEP seems to be in a better position to solicit feedback from readers / professors using the book than other operating systems textbooks. Remzi was quite prompt and appreciative when I sent some suggestions.