I think it depends on your level of experience. For someone who's a beginner to Clojure and functional programming but wants to use Clojure as their home environment for working through the concepts presented in the book, I suspect they would face some challenges translating the semantics of certain examples in the book, such as streams, to their closest Clojure representation. If you're primarily concerned with just working through the material in the book, you may not want to have to deal with that overhead straight away.