I can't see the interest of people to expose their life to the world.
And even if they limit access to "friends", that usually is about 100 or 200 persons.
Besides, Google gets all your information to add to the tracking they usually try to do on all of us.
I agree. With Android, Nexus, and Glass, Plus is just another way to track you. To see who your friends and family members are, and your interest to be exact. And oh, were you live.