Just had to add my voice to the other voices explaining what's up and what's the point.
I dropped Facebook about six months ago because of frustrations with privacy issues (and the arrogance of the people running Facebook regarding them) and trying to communicate with my 500+ friends all at once. It just drove me nuts. I also felt like it was a time-sucker without a particularly worthy purpose (partly because my hands seemed tied in many potential areas of communication because they didn't necessarily seem appropriate to my whole network of friends). It seems so designed for hype and making people stay on more.
I've been on Google+ for almost a week and I really like it. I'm sure it has some of the Facebook potential for addictiveness (and I'm sure there's more to come), but to me it has a classier and more honest feel. It's not only great as far as simple privacy goes, but allows for communication to and from your own carefully selected "circles". Circles are double-sided. You can use circles to read only posts from selected people (and you can jump between your circles very easily) or share your posts only with certain circles. Beautiful! This really opens up the communication potential with a much broader group of people and allows for elegant interaction in one account between varying realms of interest (including friends, family, fellow-hobbyists and all sorts of other things).
It has the potential to be a more elegant combo of both Facebook and Twitter (aside from the required shortness of Twitter, which can, at times, be more "elegant") because of those circles. You can post public content for anyone to see or share with anyone you choose. By the way, you can choose either groups of people "circles" or individual people to add to the list of those who can see a particular post. There's also a way for those you share it with to see how limited the post is. There is some trust involved that the people you share private stuff with won't pass it along (though there is also an option for disabling a particular post).
What I'm liking in the end, aside from the user-selected privacy options is that it provides a friendly and safe forum for collaborating on things with people you don't know very well, but that have common interests with you. I've already experienced this today when asking for help finding a quote I needed for a project I'm working on. I can imagine a number of my projects that would be aided in this way.
And so basically it offers Facebook's connectedness and Twitter's information-sharing strength with a broader collaborative angle that I haven't really seen elsewhere.
Oh yes, and one more big bonus on the privacy issue (again it comes in two parts): the names of your circles and who belongs to which circles are known only by you. Very smart.