Mt facebook page is fairly evenly balanced between writerly stuff and personal stuff. I would say about 90% of the friends I have on there are writers, publishers, artists. It's certainly a window for your writing, and also easy discussion about films, media, etc with likeminded folks. I don't know a lot of people who have been hacked and I would imagine the risks are fairly minimal. Levels of banality depends on who you choose as your friends! I'd say it's probably worth it but it can also be very easy to waste time there and sometimes I hear people getting into arguments about very trivial things.
I'm also on twitter, which is almost purely a promotional tool. It's good to have outlets where you can immediately share details of publications etc, but also a delicate balance between that and seemingly spamming everyone with your book. Best thing is to establish people as friends first and then mention anything you have published. Befriending someone to immediately promote something is frowned on (not that I imagine you would do this!)
Either way, seek me out on either of those platforms if you decide to jump in
