The dislike is because when used incorrectly it can be a hell-hole.
When used correctly, with proper securtiy settings etc and not taken too seriously, it is actually a pretty fun avenue of social interaction.
I understand why FB have an age limit, as unfortunately not all parents are as responsible as me (and others like me) but it really isn't the devil incarnate, unless you friend people who are nob heads or are a nob head yourself (years of research including a short time as a nob head myself, have led me to this conclusion).
I am hoping that by the time DD reaches optimum FB drama queen age - 14/15, she will be so bored by it that it won't register on her radar. There is method in my madness.
FB is like Marmite. Love it or hate it - no in between 