I joined Google+ yesterday, and honestly, I had NO idea what it was about before that! But it turns out, it's a social network...and I love it! It seems like a grown up version of facebook (which is very refreshing) but without the poke. Which is quite a shame as I'm a BIG poking fan....but that's another story :p
Anyway, I really recommend it. You can sort your contacts into "circles". For example, you can have a circle for friends, one for family, etc. And like any other social network, you can add pics, chat...even "hangout" with people in your circles via webcam.
At the moment, my G+ feel like an extension of twitter, as most of the people I've added in my circles are the tweeps I already know, but I'm sure as my circle grows, it's gonna be even more fun.
I'm still learning more about it and trying to get a feel of it. So if you're on Google+ also, please feel free to add me to your circles! :)