As Caspar says much depends on the person at the keyboard
I have seen some bad things on FB, racist comments, twats posting video's of joyrides in nicked cars & have heard of kids being bullied on all of the social media platforms to the point of suicide, this last saddens me & makes me angry at the same time
On the other hand I have seen lost kids, old folk & dogs found through the power of FB I have even known of nicked bikes being spotted & recovered so there is some good in it if used with some decency & common sense
So there is both good & bad in there & its all mixed up together so you need your own decency filter firmly in place to use it in a responsible manner, I don't particularly like FB but use it in what I hope is a reasonable responsible manner
There isn't a 50/50 option available so I have not voted here