Personally, I love the idea of intelligent Magic Books. Even a one-use item like the Book of Vile Darkness. How cool would it be to give it a telepathic communication method, and have the book continually goading the owner into reading it? The little, evil voice in the back of the characters' mind, tempting him with promises of power and glory...
Plus, if you give the Book abilities as an intelligent magic item, it has some use besides just what it can convey by reading it. The Book can invoke Detect Good, or whatever, for its' owner.
Lots of neat options open up. ALL the Book magic items in my campaign are sentient. Of course, there's only been one so far, and the players didn't even have it for an entire session, so I can't really say how well this plays out in the long run...