I haven't read the book in detail, although I've read the course notes it's based on. He has you build (in Scheme) a number of interpreters for a variety of small programming languages. They all share the Scheme syntax, but they have different features than Scheme, so you can see the benefits of each specific language feature and how you can implement it. By the end, you've written many different interpreters, including a compiler for a functional language. (I'm not sure how this compares to SICP, but I get the impression that it covers similar ground.)
At the time, it was an eye-opening experience: I learned that a programming language is much more than just its syntax, and that adding features to a language has both benefits and drawbacks. The section on compiling programs functional programs by automatically rewriting them in the continuation-passing style was particularly enlightening.
At the time, it was an eye-opening experience: I learned that a programming language is much more than just its syntax, and that adding features to a language has both benefits and drawbacks. The section on compiling programs functional programs by automatically rewriting them in the continuation-passing style was particularly enlightening.