As I said, if the scores on the G+ buttons here is anything to go by ..the majority here are not interested..
btw ..the BBC does not have a G+ button ..it has all the others..the BBC is one of the biggest and most visited destinations on the web..and they too think, G+ ..meh..
I don't do social ( FB Twitter etc )..and only have accounts to defend my companies names being registered by others..
Compared to the other social networks there are not plenty of people registered with G+ ..especially if you discount the ones forced into registration when firing up an android device for the first time ..without them you can cut his numbers back by at least 80% , which means that the growth of active G+ accounts has stopped and his "active" numbers, are "actively" going backwards / downwards..
There were many well researched articles ( not sour grapes ) on many tech sites about "Larry's G+ numbers" and forced G+ sign ups via first time android sign ups, around the end of January early February of 2012
You can start a "how to market to G+ circle" inside of Larry's party..you'll find far more "believers" there..all 10 of them..