The card sorting exercise has been active for 1 day. So far we've had 22 participants, about half of which are staff.
The comments I've received so far from patrons are that they were confused by the format. They expected a traditional survey and instead got an "exercise". To help alleviate this confusion I pointed the link to the Library's blog entry about the exercise. It describes a bit more clearly what the Survey actually is.
I really hope that helps clarify things for our patrons.