I didn't get it, either, for a long time. But spend a little time with it, hook up with some friends, start following people and organisations that interest you, and before too long, you'll have more useful information and interaction than you can deal with. And some good jokes.
Personally, I don't have a great deal to say on there. I'm a bit private, not organised about it, nor do I use it as a business tool... but it's a way of keeping in touch with people and news with very little commitment (if that's what you want), unlike a FaceBook page or emails.
There's a very good reason why it's taken off so quickly, and that's because it's powerful and easy to use. Those who dismiss it out of hand are only depriving themselves of something that is extremely useful.
I follow a bunch of nice people here from MacRumors, some other friends, some news and political commentary stuff, some music news... and of course,
David Lynch.