I'm not at all surprised. A lot of the book greatly undermines Catholic ideals. If it's true, then the Church spent 2000 years hiding the fact that Jesus had a wife and that a great deal of what they said about his life is wrong. Of course they're going to be upset at a movie if it reveals their secret. And if it's false, then they'll hate it for the same reason, except that the book makes it look that way when it isn't.
in either case, the fuss is totally understandable.