I've been playing with Google+ over the last few days. It's an interesting service — a mixture of one-way and two-way communication, bits and pieces from Facebook and Twitter (arguably the 800-pound gorillas of the "social web"), new metaphors to wrap one's brain around, and extremely fine-grained control of information sharing for the anal-retentive or paranoid types.
So how is it? It's quieter, because not as many people are on it. Facebook is a deluge, Google+ is a trickle.
There's a Twitter-ish one-way aspect of being able to "follow" someone without them reciprocating. You can put people in "circles" (basically categories) and share thoughts / links / etc. with only people in those circles. (Facebook has the same thing, but it's much more prominent in Google+.)
You can edit posts after the fact, and you can limit if they can be commented on or shared via the service (though I guess copy and paste is always an option).
There's built-in video and voice chat, though I've not tried it yet.
You can quit the service whenever you want and remove all your information from it forever. (Supposedly. Some [like me] would say if it's on the web, it never becomes "private" again.)
No apps or advertising, no pages for businesses / bands / etc. Yet. If it grows they'll have to monetize somehow, so I have no doubt we'll see ads one day.
It's early, so it's hard to say if it's a hit — but I think it's worth checking out and kicking the tires, and it's especially worth getting a peek before it becomes littered with Zynga apps and ultra-targeted advertising.