We'll see. I agree that Facebook Groups is much less powerful than Circles and much less fundamental to the core Facebook experience than Circles is with G+. On the other hand, Facebook Groups takes less effort to use - each person does not need to sort their friends, a small number of curators can organize the group. More importantly, it is clearer to the user just what is going on. I have been trying to talk to as…
There are a number of areas in G+ that seem like they're going to lead to highly-publicized mistakes, and the asymmetry of circles is certainly one of them. You basically have no way to know who can see your comment on a post (outside of the fact that everyone can see it on a "public" post). I also suspect an Weinergate style mis-post of something that was supposed to be private will occur fairly early on. Though to…
On private posts, the word "Limited" appears next to the post, on which you can click to see who it's visible to. It's not as obvious as it could be, but it's there.