All the social networks now have at their core what I call the River of Crap. That is the central news feed that is pulled from your contact list and what they choose to post or "share". It is effectively a newspaper, where the writers and editors are your friends/contacts. It really can be a river of crap, but luckily you can filter it. Some of it is advertising, just like a newspaper, and some of it is truly interesting and relevant.
Facebook and Twitter and Google Plus are a form of personal branding: it has become how we tell the world who we are, and we do it by showing others the things we like. A few decades ago we did this with bumper stickers and T-shirts and baseball caps with logos on them. Now we do it by posting on a social network instead. When you share a picture of Obama with words superimposed on it, you are making a statement about yourself. When you Like a post that criticizes Susan G. Komen foundation for pulling funding from Planned Parenthood, you are essentially putting a bumper sticker on your virtual car.
Facebook and Twitter are also editorial services, where the editors are people you know. The most common reason stated for not liking Facebook, or not wanting to participate, is the sense that you have to constantly read about "what other people had for breakfast." While that's true sometimes, it misses the point.
I used to monitor Google News every day, and sometimes I still do check it. But it is an automated filter, and it is not nearly effective as my own personal Rivers of Crap. If anything interesting or important is going on, I read about it first on a social network. Don't you?
There are slight (but important!) differences between Facebook, Twitter, and Google Plus when it comes to the River of Crap, and how it gets filtered. This may well be the sorting algorithm by which the winner is chosen, in the long run.
Facebook has some hidden algorithm that decides what you should see. It's complicated, and doesn't feature all your friends equally. Everybody notices this, and nobody really likes it, but you can't quite tell what it's not showing you, so nobody complains all that much about it. It is a filter, but you can't control it. The remaining filter controls are all basically "hide" in one form or another. If you don't like a post, or a person's posts, you can hide it, or them, from your Feed. When I talk to people I realize that most Facebook users don't really use this. They just accept the River of Crap for what it is, and use Facebook more or less based on that. That is probably why Facebook tries to automate the filter on your behalf, because few people take control and do it themselves.
Twitter doesn't have filtering, they have Search. Your River of Crap is just there, scrolling by, and perhaps because of the real-time focus and 140-character limit, people post a lot more frequently to Twitter than other networks. It's a faster flowing River of Crap! But to filter and decide what you want to read, you end up using #hashtag searches to follow topics. Less good as a newspaper metaphor, but better for research, because you can find information posted by people whom you are not following.
Google Plus introduced Circles as a new way to aggregate the people you're trying to follow or pay attention to. It is complicated, both in terms of posting (do people really make the decision to post to circles other than Public?) and in trying to use it to filter what you read. And it combines the two-way nature of Friends lists (facebook) with the one-way nature of Following (twitter) but in doing so, it confuses most of us. Frankly, the whole thing doesn't work very well yet as a social network. But it is a more powerful mechanism in the long run. Like many powerful mechanisms, if nobody uses the power, and people just stare at the River of Crap and decide whether to participate or not, it will likely not win hearts and minds.
What's interesting to me is that the people who build and run these services don't seem to understand what they have built. They don't offer Newspaper-like filtering, or topic-based viewing, or any other way to control the River of Crap. They still think they're building networks of Friends.