Another revelation with CLOS is methods are not namespaced to classes. Before I used CLOS it was not obvious that methods were serving two distinct purposes (specialization and namespaces) within other OO languages.

Interestingly enough, most OO systems for lisp older that CLOS were much more smalltalk like in this sense, so there were several people that found the non-namespaced approach to methods to be superior.

I'm honestly not yet convinced they are superior, but they are clearly more generic, in that it is trivial to implement single-dispatch message-passing style methods in CLOS, but much harder to do the reverse (several patterns in the GoF book exist just to emulate multiple dispatch).