It's great as long as you're the guy making the tweets, videos, and status updates that hundreds of thousands of folks read, admire, and share. But if you're some poor slob who did something stupid and are on the receiving end of a viral attack? It deeply sucks in a way that having crowds mad at you has never sucked before.
You don't get stuff for free. Yes, it's better, but cliques of hundreds of thousands of people thinking in sync is pretty freaking scary too, if you ask me. Have we all forgotten how mobs act?