One thing that strikes me about common lisp libraries, beyond quicklisp per se, is the number of libraries available. I've been away from common lisp for all intents and purposes since 1989. The total number of libraries, and the number of library alternatives in any one feature area, are nowhere near those for the currently popular languages like java, ruby, or python. However I am impressed at the ease I've had finding what I am looking for, and then installing and using these libraries with ease.
I can simply say my recently renewed engagement with common lisp has been more than satisfactory on this front, and others I'll write about later.