This is something that has been discussed ever since the birth of social media. Obviously, there are both pros and cons, and I think Facebook especially has some great benefits of use. It is worth considering if the cons outweigh the pros, though.
On the subject of personal use, if you find yourself compulsively checking it and/or getting depressed over the content, I'd say you should take a break.
As far as society goes, I think no matter how much people rant and rave, social networking is here to stay in some form. Does that mean Facebook forever? I highly doubt it. Everything has its time and then fades. Something new will replace it. And something new will replace what replaced Facebook.
Notice that each generation has its worries about the future of society and that each generation thinks the next one is the worst, the spawn of Satan himself, convinced we are going to destroy ourselves and each other simultaneously. And yet we are still here, and living longer than ever.
Even so, the misanthrope and pessimist in me can see how these trends might destroy us, if not by wiping us out (unlikely but not impossible), then by destroying our "souls" (aka our personalities, emotions, etc.). People will be miserable. I swear global misery is rising despite us being so "advanced" and luxury-laden. But then maybe that's just because you hear about it more, due to easy access to more people, globally, 24/7.
>>Edit: Strike that; while it's not necessarily pure
misery that has risen/is rising, according to the article people are now more lonely than ever before. And
that makes us miserable. So it's true, then, people are now more unhappy than ever before.
Well I wonder why... let's see... We have images of what we are supposed to look like constantly bombarding us, we are increasingly fast-paced, we are increasingly isolated and cyber-socialize more and more, we eat crap food and even the "healthy" food is loaded with s***, nature is being demolished, more chemicals in the air, the music on the airwaves SUCKS (oh sorry, that's only my personal opinion and has nothing to do with people's overall happiness... supposedly... ahem). Yeah.
Well, went off on a rant there but it's related, so I won't apologize