Structure and Interpretation of Computer Programs covers topics not often covered in other books, such as abstraction by functional composition, to give the reader a solid understanding of computer science.
This isn't a book you'll glean direct practical tidbits out of, an introduction to not only functional programming but how to think in a paradigm outside the usual way C*/Python/Ruby/Java/etc... are coded.
Even if you wind up never working in Scheme or any other primarily functional language, the tactics and thought processes you'll learn here will apply to any currently-evolving language to a greater or lesser degree. You'll be able to map your thought process into the paradigm that works best for your current situation and not just be forced into a limited set of idioms that causes unnecessary boilerplate and clunky code mangling.
Structure and Interpretation of Computer Programs is better suited for developers who are at an intermediate or higher level. The concepts presented can be difficult to grasp for someone who hasn't spent a lot of time programming.
"The Little Schemer" does touch on more advanced Scheme concepts, however includes only a weak explanation of them. For more advanced topics, the sequel "The Seasoned Schemer", is required.
The book doesn't feel very "pragmatic". The title implies a practical approach to Haskell, but it takes way too long to be able to actually create something using this book as lot of time is spent on theory.