Competition can be a very a good thing. Google+, after a little initial hiccup, rolled out a highly functional mobile app (Android's was more functional than the iPhone's, from what I hear) with resharing, user tagging, and a nice interface. Facebook now responds with v1.7 for Android after a number of incremental updates, albeit slowly, with tagging, a photo swipe interface, and a slightly more functional design, the former of which features should have been available a long time ago. Maybe Facebook would have done this eventually anyway, but their app has been notoriously mediocre for quite awhile now, until today.
The more users Google or any other social network can siphon from Facebook the better. If Facebook continues to feel meaningful pressure from its competitors, Zuckerberg's crew will continue to add features and improve their own service.
Now if Google would only integrate Reader with Google+ I'd be ecstatic.