I'm goind to share a bit of my personal experience with Facebook.
In my case, seeing the happy lives of others always makes me feel deeply depressed and blue (never angry), because i can't have that, because i cannot have a single moment of happiness since several years ago, so i have been trying to avoid all that wether in my everyday life or online, and i try to focus on myself and my own life.
I realized that many of those contacts (who i never met personally), only used their accounts to show off, they "supposedly" never had problems, they always pointed how perfect and happy their lives "supposedly" are, like fairytales, with few effort and work they "supposedly" got lots of money and travel around the world, etc, yeah right and i'm the queen of England, so then i understood i was relating to the wrong people, who were mostly faking and posing, who were doing nothing good to me and nothing for me, while i barely spoke with my real best friends, who have been always there for me, but i just ignored them for a long time.
All this situation led me 2 yrs. ago to finally leave that circus that my old and useless FB account was and create a new one, but this time it would be strictly private, only for family and closest friends and i have kept my word to myself til today. There i only have 23 contacts, between relatives, the man i love, and my dearest friends, and they are not the showing-off type, they use their accounts same as me, to be in touch with their beloved ones and share special things despite distance, they are down-to-earth people with good and bad times, with problems and happy moments, with financial prosperity and crisis periods, with a pretty much average lives, not fairytales.
So now i feel way better in that aspect and more comfortable when i login in, i give the best use to this social network that i can, and most important, i spend much less time there than before. While i'm online i finally have important things to share, and things to read that really matters to me, events to attend, familiar conversations to have, because i'm living my real life outside a bit more and my friends are genuine people who also live their real lives.
I admit that my daily routine still includes several computer hours but 50% is because of my job, and the other part had to do with mp3s, watching online series or movies, reading interesting articles or ebooks, checking weather/maps/bus or plane tickets, making online purchases, and just taking a short glance at my emails and fb.
Well that's my own experience, i won't advise anyone because i'm not the best example and i don't feel ready to, only wanted to write my little contribution to this topic.