Twitter is less to worry about than Facebook. No worries about who can see what, or finding information that was posted somewhere obscure, or having to deal with loads of email or spam or invitations. I think I like it more (in theory) because it is akin to blogging rather than a do-all website like Facebook. Then again, I dislike it because people think I want to know every little thing about their lives.
My experience is partly because I don't have a personal Twitter account, so I'm following people who I don't personally know. If people I actually talked to were on Twitter, it might make it a great deal more fun.