The problem I see Google + running into is the same as Wave and Buzz. Its not user friendly to the casual users. It has all the option and integration, but its too "dug in", too complex, too many clicks. (Puts my casual user hat on) When I go to Facebook.com, Yahoo.com, hell even the dying and spam ridden Myspace.com, everything is right there on the home page. Whereas when I go to Google.com, Im just at the search engine (which is fine by me). Most user do not want to operate the social network through their email address, They want it to be separated, hidden even, except to the people the chose to have it (their email address that is). What Google should have done was separate this Social networking experience away from google.com and have its own "default" home page. However I understand Google wants to get away from fragmentation (see Ice Cream Sandwich) and they want everything in one place, I just hope for their sake, if they want to take on Facebook, they need to be a little more user friend and more "out there". Also one of the main reason Twitter and Facebook is so popular, is because of one thing (well maybe not just this one thing, but) Gossip, and Celebrity interaction and being anonymous. With G+ being integrated with your gmail, I see that as holding it back from taking over. No celebrity wants their social media this close to the personal email. And no jack ass wants to rant and rave with their gmail right on the other side of a click.