Common Lisp definitely has a lot of "vocab" that to someone new is difficult to read. I've read The Little Schemer and the first four chapters of SICP and I feel I have a somewhat strong grip on at least the vocabulary of Scheme. I just picked up "Paradigms of Artificial Intelligence Programming: Case Studies in Common Lisp" and I quickly realized that Common Lisp is a behemoth compared to Scheme.
I can tell nightmare stories about even benign-seeming features like multiple-value returns.
Of course, I'm sure a lot of programmers out there can use these features to write beautiful code; I'm just saying that they can also be abused.