If Google can successfully integrate its already-popular properties (Youtube, Gmail, Search, Docs, Android, Calendar, Maps, Reader, quite a list!), I think the G+ service will be more useful than Facebook to a lot of users, including me.
Getting a critical mass of people is a challenge that most social apps can't surmount, regardless of their features. The large number of Google users across its various services makes a critical mass of users attainable. All by itself, the little numbered notification box they've put in the corner of Gmail should be a nearly irresistible draw into the service. My obsessiveness will probably not allow the number of notifications to just ascend, unattended, and I bet I'm not alone in that.
Whether either Google or Facebook will provide sufficient legal (and practical) privacy protections is far from settled, and beyond the scope of this piece. From the corporations' perspectives, privacy controls are important only insofar as they let users feel comfortable conducting a lot of business on their services. And after a few hours use, I'll say that G+'s privacy settings seem much more intuitive. The "view as" box on my profile lets me make concrete decisions about actual items and people. Facebook's approach asks users to make privacy decisions at an abstracted remove. The features analogous to "Circles" are very clumsy to use, which means hardly anyone uses them.
Facebook's failure to create straight-forward and transparent privacy controls (along with a string of PR disasters, versus Google's single "Buzz" misstep) has retarded its expansion into realms where Google dominates it, such as document storage, calendars, and e-mail. Facebook gave everyone e-mail addresses a while ago, but I've never had anyone give me an @facebook.com e-mail address, never seen one listed anywhere.
The reservedness associated with public performance adheres to Facebook, and there isn't enough intuitive indication that e-mails stored on Facebook will be kept private. On photo-sharing, Facebook beats everyone else, but even here, Google's privacy controls could help it rapidly make up ground. While it's not impossible, on Facebook, to withhold photos from selected people, it isn't easy. My impression is that most people just share all photos with all friends. On Google, selecting which circles will see photos (Friends, Work Friends, Acquaintances, Suspected Stalkers, Family/People You Dislike But Can't Afford to Offend) is easy, and the choice is presented explicitly every time you upload.
And if you're still afflicted by free-floating anxiety that your boss will see something untoward, just type her name into the "view as" box and confirm that all is well. The "view as" feature alone does a lot to improve confidence, and if Facebook is smart they will adopt it and much of the rest of Google's filtering approach, in short order.
The integration possibilities for the services listed above mostly suggest themselves. Isn't it handy that they have their own web browser and mobile operating system? The combination of more robust privacy features with Google's suite of free office apps might make G+ a more hospitable place to conduct business than Farmville--err, Facebook. Google already has some experience providing services to business. I bet they can set something up that will pass muster with a corporate IT department. The ambition driving the failed Google Wave project may yet be realized.
One last factor that may help this service catch on is not even Google's doing, directly: the very newness of G+ can work in its favor. On the Facebook of a few years ago, the limited usership acted as its own social filter. The earlier Facebook collected a tech-savvy (and, in the beginning, exclusively collegiate) subset of all the people I knew. A lot of people found it very satisfying to exist in a virtual world free of great-aunts and country cousins. Now, almost everyone I know is on Facebook, great-aunts and country cousins included. The "cool factor" will draw those hip, "in the know" early adopters, and then, Google hopes, everyone else will follow.
Google has already made the verb "Google" into a synonym for "search." I wonder if they'll succeed in doing the same for the noun "internet." And if they do, can we trust them not to be evil?