Interesting perspective from Will Price.
"Moreover, Google+ instantly changed my sense of Facebook's value. Prior to the + launch, Facebook's ascendancy and victory seemed written in stone. 100s of millions of users, no competition, brands flocking to Fan Pages, etc. In my first + session, I realized how easy it is to switch from Facebook to + - outside of my contacts and the occasional photo, leaving behind Facebook, just like I left Blackberry behind to go to the iPhone, proved a no-brainer and truly easy."