I'm trying out Google Plus, because I'm a sucker like that, and also because Google already owns most of my life, so what's the loss? (Copies of my diss on GDocs, etc.)
Apart from a brief exploration of Facebook (which is ridiculous), I have hitherto confined my internet activities to the public: a blog with my name on it, a Twitter account with my name on it. This seems to me to be right and just. (Well, I am pseudonymous on one other social network that will remain nameless but which is by far the best designed and most useful social network I have ever seen.)
G+ offers the same temptations as Facebook: the walled garden, the ability to form little clubs. That's both the good news and the bad news, I guess.
I've heard it said (a lot) that big search is dying (because spammers and similar are so good at SEO) and social search is the future. That strikes me as likely. This changes the nature of the "publicness" that I've tried to maintain in my web presence, but I'm not sure how just yet.
It occurs to me that there may be a day when G+ has nicer integration with Blogger blogs than just the ugly "+1" button, since both are Google properties. (The social network that shall go nameless has fairly nontrivial integration with blogs.) Blogs are said to be an old new medium, but I still like them. They're a damn good place to put text.
A note on commentary through taxonomy:
One thing I love about Twitter that G+ doesn't have is hashtags. This is a feature of its nonpublicness. Tagging is one of the best things about the web; commentary through taxonomy has become standard, and this is a curious and lovely thing. So far you can't really do it with G+. But this is the internet, so I'm sure people will eventually find a way.