I don't disagree with your distinction between Google+ and FB, but I disagree with the conclusion that its taking off. There's no doubt that Google+ is trying to occupy a different space than facebook, but I see no proof (I think any of the 'active users' stats Google touts around are more or less fraudulent) that they're doing any better than their two biggest competitors on either side of the spectrum: LinkedIn and Twitter.

it's showing itself to be a better product

How? Because in my mind the #1 feature of a social network, regardless of domain, are the social interactions it enables -- and right now Google+ is losing to the likes of Branch and Quora in that department.