Anonymous has campaigned for some serious issues. Against Scientology: I am all for that. Those bat-shit loonies are actually actively recruiting journalists and may have some politicians already part of their bizarre cult. Promoting and attacking the enemies of Wikileaks: this is a serious issue our world now faces. Though I detest what Wikileaks had done this is an important matter of freedom of speech. Where do we draw the line? When is the government right to keep its secrets?
They are not a blight on society as far as I can tell. Even if they did hack Sony, it was a couple of month's of lost updates to me and a slap in the face to a company that really was being a dick.
As for Facebook, I think they may be right about this for one reason: Facebook is sharing private information with authoritative governments such as Syria and Egypt. Social networking sights are an important component of the Arab spring, allowing for means of organized and peaceful protest only available by word of mouth before. By giving out user's information to these governments they have given the means for brutal regimes to seek out, intimidate, torture, and murder people who only want to be free. Facebook has blood on it hands.
I actually do use Facebook. It is another means I keep in touch with folks and I do know that the information I put on their is being shared freely with the government and advertisers. Right now, I am fine with that. I have nothing to hide and as backwards as my country is being right now I see no harm in it. I am using a service.
However, I don't live in a country that actively shelling its own people.