LISP is the perfect programming language. It is so perfect, it is shit. Well, okay it is not shit, it’s awesome, but when you first try to learn it, it is completely shit. It is the most obscure, abstract, whacked out language ever thought up. But it’s perfect. It is so elegant, and so simple, that you just can’t believe it works that way. What makes LISP difficult to learn is that you spend half your time unlearning deeply ingrained prejudices about how things can or should be done.
Getting over this initial hump is the hardest thing about learning LISP. Oh, and the documentation can sometimes really suck. If LISP had PHP style documentation, it would totally rule. It would rule everything.