I don't think that anything (including Facebook) is inheriently good or bad, it's what people do with it. And even what people do with it isn't inheriently good or bad, that's just our judgements. Everything just... is.
But from my subjective point of view, I really appreciate what facebook has done for networking. It's so much easier to contact my friends or whoever I need to. The people who post negative status updates, I typically "Hide" all their statuses.