In technical fields, like medicine, or even computer science research, I'd pay close attention to such commenters.
But a product like Google+ was made for the masses. Just like Google.com was. Just like Facebook was.
So until my non-tech friends start praising Google+ as if it's a must-see movie, or a song I have to hear, or a restaurant I have to try, I'm discounting these views.
I'm not saying Google+ won't be successful. I'm just saying that the people who are saying it's going to be The Next Big Thing aren't the people who make The Next Big Thing, The Next Big Thing.