I have deleted my Facebook account a long time ago and I can confirm that I can live very happily with no Facebook around.
This article by Robin Dunbar (did you know about “Dunbar’s number” ?) is very interesting however. It does say that Facebook can be a positive thing. But it also says:
Yes, you can “friend” 500, 1,000, even 5,000 people with your Facebook page, but all save the core 150 are mere voyeurs looking into your daily life.