FB is only what you let it become. There is no negative aspects of it that you have no control over. Don't want the world to know what you had for dinner and where you had it? Don't post it. however if you and some friends want to plan on a place to go eat, FB makes a nice central hub. "X" just graduated and FB makes a nice place to share those pictures. You can actually choose who among your friends and family get to see what. Uncle Don can see "X"'s graduation picture where Uncle Same can be blocked, yet retain them on your friend list.
Stuff like FB and Twitter are pretty well integrated into our society now. If a person has kids, I suggest you have FB to help monitor them and teach them the proper way to use FB.