The book covers Kafka in great detail, with all the essential elements for configuring it properly as an administrator, and also using it properly as a developer, including common pitfalls to avoid.
It has solid theoretical parts about how each component functions, as well as practical parts to follow like a tutorial. I personally attempted to navigate it using the Node.js client (thus realizing all the missing features compared to the Java one), and I would say using or knowing Java is not really a prerequisite to get significant value from the book.
On the downsides, sometimes the book's vocabulary can be challenging, especially for non-native English speakers. Additionally, it mainly covers the core parts of Kafka, and not the wider event streaming ecosystem, even though I guess it may have needed 200 or 300 more pages to do so. And I think I would also have liked a bit more detailed comparison with MQ-style message brokers.