I have had both a MySpace page and a Facebook page for a long long time. I don't use MySpace very often, but am completely addicted to Facebook. It's easy to use and a great way to keep in touch with friends. When I was in college, Facebook as THE way to get into touch with someone. More than any other social network, Facebook is the wave of the 'future' in my opinion.
I'm totally a member of many groups on Facebook. Some of them are silly, some serious, but all help to reflect the person I am. These groups give me the opportunity to connect with other people that share my interests. (I even have a friend who's now dating someone she met in one of her groups!) It's a win win situation for all those involved!