I log into FB about once a day and see some pictures of friends who live far away and their children. Sometimes people post funny things. A couple of friends occasionally post interesting or thought provoking articles. My experience as a user is almost entirely positive.
Meanwhile at some level I know it can and is being used in abusive and bad ways. Cyber-bullying, sure. The ever-present outrage machine, pitting the God-loving Americans against the God-hating ones, certainly thrives there. And I once read something or other about enabling horrible hate crimes in Myanmar. And the company itself seems to be a scandal factory, bent on a kind of dystopian mission of collecting data on everyone.
I do struggle a bit with how much to blame the company versus, well, the people who are misusing it. I think a constant lesson of this whole internet thing has been: you can develop the most utterly amazing tools ever, but at least some of your users will take them and use them to be absolute shits.