I use facebook fairly often with a few friends and out of town / state relatives. It's a good way to stay in touch and send photos, etc.
But, I'm not in to all the different games either.
I keep my info. pretty private and don't try to befriend someone just to make my list of friends grow, as some seem to do.
It can be fun but I usually only spend about 10 minutes a day on it.
It does seem to be taking the place of regular e-mails though.