After about 90 days of trial on invitation-only mode, Google+ is now open to everybody.
For those who don't know, Google+ is the social network platform of Google, with several interesting features like Circles, Hangouts, ...
For example, you can see my page on Google+.
Personally, I find this social network very interesting, but there are not enough people on it to concurrence really Facebook and the others networks. Don't hesitate to give it a try, it's worth it!