I opened a FB account for two reasons:
• Invitations to social gatherings.
• Remembering names of people (Which I'm horribly bad at)
FB helps me with both, and that is merely all I use it for (Well, apart from posting a funny picture once in a while.), since I don't see other uses for it. But it *does* make things easier when arranging social gatherings, since you can easily see how many is coming, and when/where. It is the de-facto standard for official invitations in my social network, simply because everybody uses it.
To the OP; don't be afraid, FB doesn't bite even though it is a unfocused gigantic something-something. You can turn off email requests for everything but party invitations (Which I also recommend doing ASAP).