Good for social networking, although it's not only site geared to social networking. If you set the privacy settings appropriately and you use facebook wisely you shouldn't run into security issues. Parents be advised that some groups on facebook are probably not appropriate for your children. It can be time consuming as well, but overall it is a good site!
All they ever do is deny that they take your data without your permission and then apologize after they are found out. Also, I'm not a big fan of the shadow profile thing.