Funny that you asked because I recently had a convo with a friend about how much I actually like Formspring.
I think it's okay. It's not fancy but it's a cute idea.
Formspring isn't worth it though if people keep giving out short or one word answers. I mean, if I wanted your one word, I'd Facebook/IM you. Or if they give you statements instead of question. Sorry, but if you're not using it for its function, then it's obviously not worth it. :)