Indeed one of the best books to understand DDD.

Although small, I do recommend to read it several times. It does not seem to have many content, but surprisingly —because it is very easy to read— it is packed with content and wisdom that you only notice after several re-readings.

It is like some movies, that you only notice some details onceyou have already watched it.

By the way... no spoilers intended but it even talks about how some funcional programming paradigms secretely follows DDD principles.