Lyle Fong, the CEO and Co-Founder of Lithium: “Active Facebook users at some point face a conundrum – either they don’t accept friend requests from all of their coworkers, acquaintances and distant family members and risk being viewed as elitist, or they accept all requests to be nice, but then find themselves having to censor or sanitize their own posts. In either case, Facebook becomes less useful over time. Google+, with their circles functionality, can be game changing if they can address this core problem.”
I disagree with Fong. I'm an active Facebook user that accepts every invitation from people I know and I still don't compromise my posts. I have friends in lists and I always share with specific lists.
Groups and Lists are to Facebook what Circles are to Google+. Nothing new there.
I think that "Sparks" is what's really setting Google+ apart here. Content auto discovery based on interest is a huge business and one only Google can do well.