For something that's in the beta stages, it runs very well. I could even put the Google+ app on my phone. It's very streamlined without a lot of the junk that makes Facebook less than desirable (like there are no stupid games on Google+).
So far, one of the best features that I have seen are the circles. You can put different people in different circles, so you can post updates to only the people you can to see. This is great if you want to put people who have similar interests together, along with separating out people you know in real life from people who are only acquaintances online.
Right now, it's pretty quiet because invites are hard to come by, but I'm looking forward to when it's live for everyone to use. I think it could even possibly knock Facebook off of its throne as top social networking site.
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