Don’t know - I’ve never had an account and have rarely even seen Facebook.
It’s interesting to me how much I can enjoy a facebook friend who I’ve never met and other people who I’ve known forever can be hugely irritating on social media. I’m FB friends with many people through my sport or even through CC, and some are so witty and interesting that I feel very connected, while people in my community circle or high school group can make me crazy!
I’m relatively new to Facebook. It’s nice seeing what my far flung cousins are doing.
I have a friend who has chronicled his journey with cancer. He’s been very honest and upfront. It’s nice to know what is going on.
My D only posts to Facebook from Instagram. That is nice because then my relatives can see what she is doing but not her Instagram stories. Because they are only Facebook friends.
Twitter for me is news and sports. And a bit of reality tv
I have only had positive experiences on Facebook. Rather, yes, I’ve unfriended a few people but that wasn’t a negative…just an option I elected to pursue. I’ve re-engaged with people from my past that I never would have connected with otherwise, I’m able to join groups related to my interests, my volunteer work, etc. that I find helpful and informative and I get updates about my friends’ lives that I wouldn’t necessarily have otherwise. I never take quizzes, don’t donate to fundraisers I don’t wish to donate to and, like I do on other sites, I ignore the ‘sponsored’ posts and ads. For me, it’s an enjoyable 20 minutes or so a day. I will say that I rarely post myself.
Pros - recipes, local hikes, books, local events, keeping up with far away friends.
Cons - everything already mentioned.
I have gotten really good at scrolling past things I’m not interested in. I can do without those “missing child” outdated posts, or "who remembers [common household thing], etc., but the people who post them tend to be people I care about otherwise (older relatives, folks that just are not that discerning in some ways) so I ignore.
I will say, the canned “I know who will post this and who won’t!” shares are irritating, but again, teaching myself to move on and not waste mind-space.
I don’t mind food pics–have participated in many cooking/eating out convos because of them.
Politics are fine. Most people I know have the same values as me, so I can learn a lot from what they post. (those that don’t, these days, may be quietly unfollowed because I just cannot with that.)
Overall, besides that I have reconnected with old friends, the most important thing is the huge writing community I belong to, and all its sub-pages, which has immensely helped my writing practice and career. (And many people there are in their twenties and thirties, so don’t tell me FB is only or old people. Probably half my friend list is younger people.)
I will say another “con” that may be CONtroversial. 
Applies even more on Instagram but also on Facebook.
The con (or annoyance) for me is when people join only to read but never post. If I friend you it’s because I would consider you interesting or care enough to want to know what’s going on in your life, what you have to offer. When people are on FB/Instagram and never post I liken it to being a peeping Tom - looking in and taking in the scenery but not letting anyone know you’re there and keeping your own blinds shut.
No cons. Yes there are annoying posts, and even more annoying comments, but I take responsibility for reading them. You can’t control others, but you can control your own actions. Annoying posts and comments are very easy to ignore.
The stupid surveys that are clearly designed to elicit answers to your security questions. The “please don’t just share this, cut and paste it so I’ll know who my true friends are” essays written by bots with heinous grammar, which are also intended for some nefarious purpose. The politics.
But I love the cute animal videos, your vacation pics, your TBT pics, and your funny anecdotes. I don’t mind the braggy posts (we all know that’s not the whole story, and I really don’t want the whole story!)
Most political posts and shares that I see on Facebook are heavily opinionated and distorted to incite anger and hate of whatever it is opposed to. Be wary of taking the content at face value without further investigation of what is claimed and what is left unsaid.
The cons for me are political posts (why do so many people think they know enough about political issues that they continually broadcast their opinions?), this dog needs a home posts (enough already!), and people who just dump all their photos and don’t cull (do they really think people care to see every single photo they take?).
abasket- I completely agree about the lurkers. I give some folks a pass- they honestly want to keep up with me and others, but aren’t comfortable posting. But- the ones that basically consider themselves too good to share anything about themselves while creeping on everyone else bug me. If someone hasn’t interacted at ALL with me in a length of time, I will unfriend them unless I have some reason not to do so.
I don’t tweet or post anything… Call me a creeper. So what.
^^^ Untrue! I understand you DO post on groups you are part of. 
You also “like” and comment.
I haven’t posted anything personal on Facebook in two years. My last post said that I looked forward to connecting with everyone more regularly in real life. I do scroll through every few days to see what is happening because as someone mentioned, you are out of the loop if completely off Facebook. An old friend from a long ago job posted about her breast cancer diagnosis. I did not leave her a heart, I picked up the phone to call her and have a real talk. Same thing with family-I’ve made it a point to reach out and try to actually see or call the people I can, aunts and cousins, instead of just interact online. I have made more of a point to make lunch dates with old work friends. Before I decided to stop posting, I also unfriended a ton of people. My circle had grown too big. I don’t need (or really have) 400 friends. I have a few really good friends and I truly love seeing their vacation pix, or hearing their great news. That’s maybe 30 people? But I did find that the rest-the people I don’t really know/care about/have deeper relationships - did inspire some FOMO and sourness in me! And then it made me question what I was posting? If they were really happy for me when I was able to go somewhere beautiful or if they thought I was a show off? So I just stopped! I needed something to break the addiction so I set up an instagram account-but I learned from my FB experience I have less than 30 friends including my family. They are my real close friends, who i know are truly interested in what I have to say, and vice versa. I’m not totally against Facebook, but I’m much happier now that I’ve minimized my time there!
I guess I’m a creeper like you, @BunsenBurner . I do participate in groups, like and comment on other people’s posts, but never post anything on my page (except accidentally). My sister set up my fb page for me, put the pictures online and friended everyone on her side of the family. After several years, I finally just friended my husband, and haven’t friended my kids yet, only a few people on the groups that I’ve participated in, and a random friend. And a few people accidentally!
What I really don’t like about facebook is when people put rude and abrasive political posts on their page. I don’t mind if someone puts something intelligent and thought provoking on there, whether or not I agree with their worldview. But just insulting and stupid things…and boy, you’d better agree with them or not question them, or they are angry. I try to just ignore it (while thinking that I’d rather not know how insanely biased they are), but occasionally I have to ask pointed questions, while trying to not offend. It seems that people think that everyone agrees with them, and they don’t realize how boneheaded they sound!
Anyone who friends me could see from my page that I don’t post. If they didn’t go to my page before they friended me, I have to question why that is if they are truly interested.
I do react occasionally and like, but I don’t post.
Well if they are truly friends or family with you I don’t know that they would bother to check out your FB legitimacy! I might do that for a casual acquaintance but I wouldn’t probably scan the page of someone I know pretty well.
You’re not a creeper, peeping tom or even a lurker if you at least click “like” on your friends’ posts. When I go through a periodic review of my list of “friends,” I unfriend those who I know have been on Facebook (you can see the green dots on the right hand page next to their names) but only to look at my posts. I know of a family friend who, throughout our kids’ high school years, had exhibited a lurking behavior in finding out about our kids’s extracurricular activities. I didn’t mind that all that much as I found such behavior harmless and amusing. But when the friend continued to exhibit the same lurking behavior once we connected via FB, I unfriended him after a year or so. But this is an exceptional case. For the vast majority of others, they just don’t visit FB in spite of having the account set up. My brother and sister are like that.
I don’t actually know how to even tell if someone is a lurker…however, I am really facebook illiterate. I just hope I don’t offend anyone, but wouldn’t be able to tell anyways. I did wonder, after I questioned someone who probably only wanted agreement, if they blocked me from making subsequent comments on anything. On a later post, I made a positive comment and liked something that was completely unrelated, and then saw that my comment disappeared. I wonder if you can do that, just make anyone’s further comments go away, no matter what they say.