The blogosphere is already full with comments and reviews on Google Plus. I won’t try to duplicate what other people have said.
I have one very quick reaction, though: I was an early Plus user, just as I was an early Wave user. And there’s one big difference. Within hours, the early Plus invitees were actually using Google Plus for conversations. Not just nattering back and forth, not just comments on the service itself, but real conversations.
That’s fundamentally different from Google Wave, where I rarely saw any discussion that wasn’t about Wave itself. It’s possible that’s just the company I keep, but I think that’s important. For a social network to succeed, people have to be social. And, while I saw loads of cool stuff on Wave, I never saw anything that was social. It was all about plugins, APIs, robots, outages, browser crashes, and the like. I never got into Buzz, so I don’t have any basis for comparison. If you have thoughts, don’t hesitate to add them to the comments.
I don’t think Facebook is quaking in its boots; I do think (as @fredericl pointed out ) that Twitter may have more to fear than Facebook. I’ve participated in exactly one huddle on Google Plus: a 3-way video conversation with participants in the US and Europe. It was smooth, cool, easy. No echoes, no long delays, better audio than a cell phone. Skype may have more to fear than Facebook or Twitter. (I confess, I’m a long time Skype-disliker).
Google Plus is not without its warts, nor should we expect it to be; it’s only been up a few hours. There is an undocumented way to invite arbitrary people. I won’t tell you what it is, but it’s not hard to discover, and that’s important: a social service won’t work until you have people to be social with. I wonder how well the “circle” metaphor scales; I already have more people in my circles than are easily visible, and I have more circles than fit on one screen. And I’d like an easier way to re-organize my circles, since I’m not sure my current organization works.
But in short, I think Google has a winner. Bugs and warts are easy to fix when the foundation is solid. Congratulations.