First: the service is invite only for the time being.
Second: the network effect can be a curse as well. Linkedin has succeeded because its network is limited to work contacts. There are costs to having a complete public network.
Third: Google+ does offer an amazing, new and different service. It's not Facebook. Facebook is built on its social network, which is the product most users want, not the features (which a lot of users seem to hate). But Facebook expanded initially by being a high prestige social network; that's changed and, given Google's invite strategy, it's reasonable to believe that G+ is now higher prestige.
Second: the network effect can be a curse as well. Linkedin has succeeded because its network is limited to work contacts. There are costs to having a complete public network.
Third: Google+ does offer an amazing, new and different service. It's not Facebook. Facebook is built on its social network, which is the product most users want, not the features (which a lot of users seem to hate). But Facebook expanded initially by being a high prestige social network; that's changed and, given Google's invite strategy, it's reasonable to believe that G+ is now higher prestige.