It is definitely much more than an introduction. There's a lot of examples and exercises, and it goes into a lot of detail on some topics. The chapter about parser combinators is 70 pages by itself. It's only an "introduction" in the sense that it starts off assuming no Haskell experience.
In a sense, it feels like the textbook for a course combined with transcripts of the lectures... although it flows better than that, of course.
