I've been wanting to write a Facebook competitor. Your $5000 is the motivation I need to see it through. It will be awesome owning 50% in the next Facebook. Let's do this!
The real problem with G+ is that I forgot about it. Facebook nags you with emails every time something happens, but G+ just has a dropdown box that lets me approve friends or not from gmail, and I never see my "wall". If they made me go to the "wall" to approve friends, then I'd see what my few active G+ friends were posting and maybe post something back. I went months without seeing the wall, even though I have close friends who work at Google and post things I'd actually want to read.
Also, the "circles" thing and their change of terminology seems like it's being different for the sake of being different, or to avoid being sued by Facebook or something. Stick to the terminology people know.
G+ should have tried an "import Facebook" feature that takes all your pictures off Facebook and invites your friends to G+. This alone would help me not care about Facebook. I have a ton of pictures on Facebook that I'll never see again if I were to close my account. Facebook might try to block a feature like this, but it's sorely needed to make the transition.