What it says on the tin. The Little Schemer is an extremely fun introduction to functional programming through a beautiful language, Scheme, but the code in the book can also be adapted for use with common lisp with very little effort, considering the first iteration of the book was The Little LISPer. The purpose of the book seems to be to teach you recursion and some functional programming, and to delight the reader, and it accomplishes that in a way that feels absolutely magical in ways most other programming books could never hope to.
Anyway, I hope more people take the opportunity to play with it. I doubt anyone even reads this blog because I never update my website, but for all one of you reading this, I ask that you take the time to pirate legally acquire a copy. It reads like a cute little Q/A, and if you try to actually write the programs in the book instead of just copying the solutions, you might learn something, too.
tl;dr - it's the good shit.