Some good insight from Farhad Manjoo:
[A] social network isn’t a product; it’s a place. Like a bar or a club, a social network needs a critical mass of people to be successful—the more people it attracts, the more people it attracts. Google couldn’t have possibly built every one of Facebook’s features into its new service when it launched, but to make up for its deficits, it ought to have let users experiment more freely with the site.
[Update: Nick Bilton brings up a good point: Even if Google+ fails to compete, it is unlikely to die anytime soon]