I confess I don't really understand the question. The handful of product pages I've Liked on facebook end up filling a tiny minority of my newsfeed. I wouldn't expect it to be any different on G+, except that I have far better control over the mix of content in my stream here (and I expect the control to become better in the future than the current all-or-one approach to circles in your stream).
The main corporate pollutant on facebook (aside from the garish ads in the margin) is all the Cow-Clicker apps that my friends spam me with as well as the malware that's infesting the site through its API being open to third-party developers. I'm not so naïve as to think that a G+ equivalent to apps isn't coming down the pike sooner or later (though here's hoping), but from what I've seen of G+ so far I'm confident that I'll be able to control how much of a nuisance they'll be to my experience here.
Other than that, and leaving aside the obvious friends vs. circles discussion (to say nothing of hangouts and sparks), G+ is different from facebook because it's a gateway drug for us all to start using all the different Google services. I'm a long-time Gmail user, but as of this week, I've started becoming a Picasa user through G+. I don't have a Flickr account, but now I'm less likely to set one up. Before long I'll probably explore the Calendar and Documents tabs on that black bar at the top, too. They've already integrated sharing with G+ identities into Picasa, and I'm guessing I'll find the same thing in Documents (and probably Calendar, too).
I'm not a fan of monopolies, mind you, but I'm going to give Google a fair shake on this, because as far as I can tell they're quite careful about how they implement their features, they seem
to be taking the right approach on privacy, and frankly I've never been distracted or irritated by their embedded advertisements (I guess we'll see what the advertisements in G+ will look like after the roll-out).
So in short, to me, G+ is different than facebook because it is already so much more
than facebook, and I expect it to expand even further as it matures.