The best thing about FB is tracking down folks you haven't seen for decades.
Yesterday I reconnected with my MTC companion. As an added bonus, he's been out of the church since just a few years after we got home.

Then I will give it an attempt.

If I don't want people to join, can I just not let them join my facebook group, or do I have to let them join and comment? There are a couple of people I hope to never see again in this lifetime.

You can search for them, then block them. It's really quite easy.

I give a "like" to FB, too. I've been able to keep in touch with HS & college friends that I'd lost touch with until 3 yrs ago. Today I reconnected with a college friend I last saw at her wedding 18 yrs ago. From an idea a classmate posted on FB, a bunch of people organized a multi-year HS reunion last fall that was much better attended than the usual single-year ones.

You can Unfriend people if you don't care for them, you can have particular postings only viewable to a select group of friends or you can block a friend from seeing updates.

You can also block/hide games on FB. That can be a particular sore point if you aren't playing that game as you will see many updates/postings from games your friends play. You can also hide individual posts from others that you find objectionable.

of course you choose who is your "friend".
There is a great deal of control you have over who can see what, and whether or not they can comment.

I'm too hungry to do that on an empty stomach. :-)

I've tried it too but messed it up a lot.

I don't like saying no to friend requests when I know the person but I get requests from people I don't even know. What is that about?

The privacy concerns also bother me. I know you have control, except when you don't, in cases of glitches and frank FB lapses.

I decided to stick with email. So far, I don't think I'm missing out. I'm sure it works great for those who enjoy it.

Adults can handle the fact that not everyone wants to be their friend. I wouldn't lose any sleep over their feelings -- each person is responsible for their own happiness (or lack of offense).

and I do not regret joining
But I see how it rules some peoples lives, so I'll set a limit to my fb time, and not violate it.

I've managed to stay off FB. I've got a big enough addiction going with RFM as it is.

When I ocassionaly run into old high school friends irl they seem so Molly and Peter that I usually cut it pretty short. So I'm not really interested in contacting them.

And then there's all my relatives on FB. Yeesh! I saw that one of them has like a thousand friends. Who has the time.

I love FB. I'm 47 and have reconnected with people I haven't seen in decades - mostly high school and college friends. It's a thrill seeing so many people I have fond memories of and watch them post things about their lives. I've reconnected with my best friend from kindergarten. I've connected with a person who was born in the same small town hospital as I but only a day apart. She & I were in the hospital nursery together as newborns but never knew eachother growing up. Turns out we had 3 friends in common and our lives had interesting parallels.

I've only unfriended one person so far...her posts were always laced with four-letter words I didn't see any reason for it and didn't want to read that everytime I signed on.

My rule is, if I don't have anything worth posting, then I'm not going to post anything. I wish everyone did that.

Wish I could say the same, but alas..... I re-connected with a missionary companion - one I really like - on Fazebook, and when I told him I'd left the Morg, he dropped me like a hot potato.

So much for "reuniting"