I'd say it more turned out that Circles were decidedly unintuitive, and far more of a pain to use than Facebook's single list (which can still be heavily customized, most people just don't bother.)
I think the circles were fine, the problem g+ had was that it lacked plenty reasonable features (events, anyone? never understood this when google calendar integration would have been a killer feature).
That's facebooks main use case for a lot of people and it's absence made g+ pretty useless.
Doesn't Facebook also have a nasty habit of surprising people with breaking changes to the way those customizations work? I seem to recall hearing of such things on a fairly
regular basis.
