Google+ will be successful because it attracts meaningful conversations and motivated users. It took the best from Twitter and Facebook and added its own flair, making it the most contagious, fun and informative social network I have ever participated in.
True that, particularly on the meaningful conversation side of things. Like many, I initially approached G+ as a kind of Facebook. I focused on basically friends, coworkers, acquaintances - personal relationships developed through assorted means. That was neat in having a replacement for my Facebook account, but I kept on hearing about noteworthy commentary being posted via links to G+ on hn, reddit, etc so I started exploring with new non-friend circles.
After branching out to my immediate interest areas (tech), a little later I ended up adding Philip Plait (bad astronomy guy), Fraser Cain and other sciencey/astronomy folks. The amazing Hangouts that these folks do a number of times/week makes me feel really lucky to have access to such a resource. Certainly having some degree of access to experts in assorted fields is nothing new thanks to the internets, but G+ has, in my view, made such interactions far more accessible.
I can only imagine that there are other groups doing awesome things with G+ who I have not yet found.
The photographers seem to be having a strong community on G+ and G+ is the place where us amateurs can be exposed to their awesomeness. And talented those people are.
In the last few months, I have noticed many HN posts linking to Google+ posts. G+ is becoming a strong blogging platform and because Google is pushing rel=author so hard, soon it won't matter WHERE you wrote it (domain), it will matter WHO wrote it (author). That's why I see A+ bloggers adopting G+ soon.
I'd see'em in Google-themed subreddits like r/android pretty often which makes sense, but in regard to the more popular subreddits, they pop up every now and then in r/programming, r/atheism, etc. kn0thing submitted a post to r/technology the other day in regard to his plans to speak to the committee on SOPA and PIPA. I think I ended up following him on G+ after that one. I also vaguely recall the 'Comcast using tricks to raise rates' post also getting a fair amount of attention from r/technology
That said, I'm pretty sure it's possible to do a reddit search for submitted links to a particular domain if you're looking for more details. (I'm a little hesitant to link directly to a bunch of reddit pages here. Don't want to step on anyone's toes.)
Anyway, it's not like G+ posts are exceeding imgur links or anything. It just seems that based on my completely non-scientific observations, I'm seeing G+ posts linked more frequently than previously (or perhaps I'm just looking out for them more often ;)).
