The only fly in the ointment for me is this: I really wish they'd set up the licenses so that they constituted a blanket waiver of Moral Rights, but I can't fault them for making it optional.
Still, if you're Canadian and you're CC-licensing your work, please consider the moral-rights waiver; otherwise, people who use your work run the risk that if you take it into your head that they've offended you, you could force them to destroy the new art they've made with your stuff.
By the same token, I will never, ever incorporate a work with a "moral rights asserted" clause into any of my works -- it's not worth the risk to me.
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.