[Galadriel55]

One change that I like about the movies is a little minor word swap that I think makes the quote sound better. In the book Gandalf says "You cannot pass", while in the movie it's "You shall not pass". I think the latter sounds better, and in a way is more true in their situation. Gandalf doesn't know if the Balrog can or can't pass, the whole point of their duel was that the Balrog was an evenly matched if not more powerful adversary, and it required all of Gandalf's power to not let him win. Gandalf could be speaking with more knowledge and authority than his limited mortal form - perhaps believing that Eru would not allow the Balrog to destroy the mission or some such, but I think it's a stretch and it takes away from Gandalf's own sacrifice. "Shall", on the other hand, is a promise rather than a statement; even though the Balrog may actually be able to pass, he still will not. As a byproduct, this phrasing also puts more emphasis on Gandalf's heroic role in the scene.

So yes, this is the only quote I can think of that I like better in the movie than the book.