Even more so than Haskell.
It doesn't have monads and the kind of abstractions that lets you modify control flow semantics. It doesn't even have the facilities to build abstract data types - which makes you work with less-abstract data, and realize that although some abstraction is useful, most of what is practiced today is useless.
APL / J / K promote, at the same time, container abstraction, and concrete down-to-the-metal real work.
Maybe more inspiration than introduction, but the "Game of Life in APL" video is a must see (http://uk.youtube.com/watch?v=a9xAKttWgP4&fmt=18)
The description on YouTube points to a "Game of Life" tutorial at http://tryapl.org. I haven't tried it, but it looks nice.
For a more academic (as in "read about, don't play with") introduction, I found Iverson's "Notation as a Tool of Thought" (http://awards.acm.org/images/awards/140/articles/9147499.pdf) a good introduction.