For readers, social media is large improvement because of all the information about writers and novels that is now available. You can find your favorite writers' blogs and learn about new work that will be releasing. You can also subscribe to blogs and newsfeed for your favorite booksellers and learn about special events, author signings, author readings, and when new novels that might interest you will be available. For readers, there's a treasure trove of information, a literal glut of data of the subject.
The picture isn't as rosy for writers in my view. For writers, social media is both good and bad. For example, social media let's you tout your work and attract an audience. That's good because it should mean sales. Without sales, we won't last long. But promoting your work can also be bad if you find it a chore or have no marketing skills.
Likewise, blogging, tweeting, and all the rest can be good or bad depending on whether you have something to say or not. As writers, the natural assumption is that we do have something to say or can find something, but the simple fact is some people are more comfortable with it than others. Some people are naturally shy and would prefer a quiet room to write in than composing a tweet.
Another concern is loss of privacy. To a certain extent, writers need to make themselves public figures so that readers can learn about them. That's good; when readers connect with writers the potential for sales goes up. The problem is some people might use that information inappropriately. So writers need to be careful about the information about themselves that they release to the public.
Bad reviews and ill-informed comments are another issue. Dealing with the public can really suck. Ask anyone who has given technical support or who has to answer phone calls all day. With social media, all these comments are visible and public. Depending on the site you might have control over these comments and you might not. So be careful and remember everyone has a right to free speech, even if the comment being made is lame or silly.
Lastly, there's the risk of intellectual property theft. By this I mean social media enables such theft to go viral. A stolen book on a torrent can spread around the world is seconds. There's not much you can do about this if it happens to you and you can't really protect yourself either. All it takes is one person paying for one legal copy to post your work on a site and recommend it highly. Other avid readers/computer users will do the rest.
But even though I cite many drawbacks stemming from social media, the truth is all these things existed before. Writers are always facing a loss of privacy as their recognition increases and they become more popular among readers. Likewise, bad reviews have always been an issue; they used to be printed in the newspaper now they are electronic. So you'll need to learn how to deal with the criticism. And theft of our work has always been an issue. It is easier now because of the technology but corrupt people at print shops have stolen the work of popular writers for years. That's why there are copyright laws in the first place, to help protect us.
So where does that leave us? Well, when I came out of my reverie, I realized that is not social media that is the issue. It is people. That no matter how much change we endure and what the tools we are using, people are still people, good, bad, and indifferent. And the struggle of getting along with each other has not stopped, it's just changed a little.