I've been of the opinion lately that the mobile app, GroupMe, is all of the Facebook I would ever need. It allows me to start group chats, identify my geographic location, start phonecalls, share pictures, and more. Best of all, GroupMe allows me to do this on a per-group basis: No all-or-nothing approach as with Facebook. One of the most compelling features of Google+ is this same breakout of friends, each with its own settings. Google knows this and plays heavily into that when promoting their "Circles" feature.
So, does Google finally have a social media winner? I see a lot of press focused on whether this offering can unseat Facebook, but I'm not sure if that is the right question. I'm more interested in the potential for Google+ to achieve critical mass, that is sizable and sustainable adoption -- regardless of comparisons to Facebook. If "yes" Google will have demonstrated that social media platforms are not one size fits all. I think this is where the space is going, and I can see this as an important learning for the marketplace.
The precedent is already here: today, we have an easy split between Facebook (for personal social and commerce use) and LinkedIn (for business). Longer term, I could easily see some fragmentation (with Facebook remaining strongly dominant), along with the rise of "social media aggregator services" that bring together streams from various sources. Again, the precedent exists: see TweetDeck and Hootsuite's ability to bring in LinkedIn, Twitter, Facebook, Buzz, and more. And, we also have products like Trillian and Adium that aggregate multiple instant message platforms.
So to pose the question a different way: Will Google+ achieve critical mass? I think, yes, that this time they might have it right. They've got a great-looking new platform with the right control settings and the right connections in place -- with Gmail, Google +1, and more. To further help drive adoption, Google will benefit from the Android OS and (soon) the Chrome OS. In the long run, Google will have an inherent competitive advantage b/c it will be able to directly bake-in to the OSes - basically becoming an ever-present service to support other activities.
It seems silly counting Google as an underdog here, but if Google +1 became a persistent, if smaller, player in this space, I would consider that a big victory for them and for the marketplace, too.