this is way too complicated for mainstream users. didn't g+ prove that the circle designs while elegant really didn't take off at all?
plus I hate their automatic lists, they're ridiculous and don't match my real-life "lists" at all.
in zuckerberg's terms, nobody wants to make (nor maintain) lists, whether you call them circles or groups or whatever. Who the hell is going to spend hours refining their circles except from super privacy conscious hipsterhackers of the SV? I bet most people would rather go back to the ol'good plain dumbphone address book.
with that said it is visually very appealing