I'm sure Deco is a good player, whenever I have seen him he has only been mediocre though.
My problem with this is that from interviews I have read etc, he seems pretty arrogant and I don't like him for it. He claims he wants to go to a club who can ensure his status as the number 1 in the world, it's all very well if you are one of the best players in the world to make such claims, but he currently isn't.
He just seems big headed and boastful which isn't Juve's style particularly, his manner would probably suit Real Madrid a lot more than Juve!