Who is to say what the purpose of G+ is supposed to be? It should be whatever you want it to be.
If you have ever seen any of the tutorials or promos for G+, they talk about "Sharing but like real life". Here are a couple of them:Google+: Sharing but like real lifeGoogle+: Sharing but like real lifeGoogle+: About CirclesGoogle+: About Circles
In the above clips, you'll see the friends, family and co-workers are one of the first things they show. This tells me that they want this to be a place where the people you know are included.
That said, it is also an opportunity to meet like minds and to explore things about yourself.
Animated gifs can get annoying, especially when I've seen the same one over and over. Eddie McBride's gifs are a bit of a break for the norm in that respect.
A public hangout would not be something that would interest me. I only tried one with my brother and it was only a small test to see what it was like. If more of my friends and family were here, I would consider it. For now, I'm fine interacting in posts and sharing what I can. I will also watch the streaming hangout for Dan McDermott's program Google Plus Week and participate in the chat room. I'm much better at writing in public than I am speaking in public.
For now, I still have Facebook because that is where most of my friends and family are. I also have some pages that I follow that do not have a presence here. We all have different circumstance and due to the fact that I work M-F, have other things to do and divide my time between two networks, I must interact wherever I can (even if that is only a few posts).