I'm trying it out, but I can't invite any of my friends and family. That kind of defeats the purpose. It's social networking without the network or social aspects.
Create an empty circle. Add them by their emails. Post to that circle, G+ will send a "X shared Y with you" email which is actually an invitation.
Does this work for you?
This hasn't worked for a couple of days at least. Yes, the invites go out, but the signup page only intermittently accepts logins (presumably as they open/close the floodgates).
I just joined G+ 2 hours ago with such an invite.
I must be missing something. When I select the 'view post' on the invite email, the interface tells me that I need an invite. Quite a conundrum!
Keep trying. Didn't work for me 2 days ago. Worked today.
Kinda. Until you get friends and family on board think of it more as Twitter, where there are many interesting people to follow and interact with and there's a bit more 'bandwidth'. I have a few of my friends on there but am already enjoying it more than Twitter.