I just wish their mobile site didn't suck so bad. I'd use it more if I could access it from my Windows Phone. But yes, I was a part of the Beta, and it's more like Facebook with very good video video conferencing and better event handling. In other words, it's a social networking site that does social better than Facebook.
I use it, got less then one hundred followers but regardless. I feel like its as stated above a facebook, twitter crossbred. It personalizes your results better with google however, and syncs it over the whole google network which is convenient. I feel when it comes to posts however its more like a professional ecosystem where you can post things that you find interesting, your photography if you do some, or blog on it. Multi purposeful I suppose.