I was a reluctant joiner of the Facebook generation. I signed up primarily to post pictures so my family could see them without a lot of fuss. FB is great for that and I do enjoy the comments. Even the "likes" which I initially thought was kind of vapid have grown on me. I click "like" these days surprisingly often.
Shortly after I signed up, my wife asked several people to "friend" me so I would not be embarrassed if I compared myself to her massive number of friends. Just getting my siblings and a few in-laws to give me a "mercy friending" got me to a few dozen which moved my number off the "embarrassing low" friend level. In the year plus I have been on FB, I think I have only friended 3 or 4 people myself - perhaps an innate fear or rejection or a desire to avoid "farmville" and other nuisance requests. I have only "de-friended" one person - a high school teacher of mine that began to irritate me with all this political posts.
Having college age kids brought complications - both our kids drew the hard line with us initially - "YOU CANNOT BE MY FACEBOOK FRIEND". Apparently both feared that one of us might turn out to be a Facebook stalker and embarrass them by putting parental advice on their wall or worse - like friending THEIR friends. I took the rejection in stride. A few months later, I was shocked to get a friend invitation from my younger daughter. I actually think she made an inadvertent click that sent me the invite but she didn't want to hurt my feelings and allowed me to stay on her friend list. Of course then she felt obligated to friend her Mom too. I suspect she used FB settings to limit our access but aside from me sending a "fatherly" message to one of her male college friends I have met I seemed to have stayed within the complex unwritten rules of intergenerational Facebook behavior. At least I get to see her pictures. My elder daughter, despite being out of college, still draws the hard line on being FB friends with her parents. Strangely both my kids are friends with many other relatives. Many of my nieces and nephews that are college age or slightly above have friended me. Yes FB protocols are odd especially since both of our kids talk to us on the phone very often and reveal details that I would never have shared with my mother or father but this largesse of communication does not extend to free access to Facebook.
Having lived overseas, I really enjoy the convenience of staying touch with friends all over the world. International connections can be a bit more complicated. The sheer volume of similar names on Facebook and names written in Chinese characters can present problems. On two occasions I have been at dinner with friends in Tokyo and had them ask me to be their friends. Even sitting next to each other with Facebook up on our IPhones, it took a long time to help them "find" me so I could be "friended". Japanese friends that enter their names on FB in kanji rather than the romanized versions have friended me. With my limited reading ability in Japanese - I normally have to get my Japanese / English dictionary out to confirm who I am accepting since some people don't use a profile picture or one that doesn't provide positive ID. My profile picture is usually a shot of my better side (the back of my head), some people use pets or other pictures.
Now that Facebook is both a noun and a verb, the question of longevity arises. Will it be as pervasive in five, ten or twenty years? I have no idea but it is another phenomena of the digital age that has changed how we communicate.