Common Lisp for Schemers

What's the best way for a Schemer to learn Common Lisp? It seems like Scheme itself is a more beautiful language, but the efforts made by many implementations to make Scheme useful "in the real world" lead to a big ball of mud™. Does Common Lisp avoid this problem? Should I keep trying to learn different Scheme implementations instead until I find something I like?

>>4
Scheme:

(define-syntax lett
  (syntax-rules ()
    ((_ exp) exp)
    ((_ k v rest ...)
     (let ((k v))
       (shen-let rest ...)))))

(lett x "fuck" y (string-append x " you\n") (display y))
Your move, Haskell wankers.
Just kidding. I love all of you.