I found Little Schemer to be too elementary. I feel comfortable with lexical scoping and recursion, I was actually looking for more meat (let vs. let* vs. letrec). I'd recommend "Teach Yourself Scheme in Fixnum Days".
_The Scheme Programming Language_ by Kent Dybvig is also very good. _Structure and Interpretation of Computer Programs_ is my preferred "how to think in Scheme" book. I would recommend against _How to Design Programs_, which is entirely too pandering and focused on imperative programming for my tastes.
'The Little Schemer' is not intended to be a tutorial on Scheme. To quote the preface, "The goal of this book is to teach the reader to think recursively". Similarly, the other books in the series have well-defined goals.
http://www.scheme.com/tspl3/