While I expected this, I'm not confident. With LOTR, I expected some parts of the story to be changed because film and paper are two very different mediums - something that worked in the books wouldn't work in a movie and vice versa.
But so many of the changes had nothing to do with the medium. Watching the movies, I couldn't shake the feeling that Jackson thought he could write the story better than Tolkien.
Instead we saw scenes such as: Aragorn falling off a cliff and everyone thinks he's dead, only to return to save the day; Denethor slobbering all over his food, yet too stupid to summon the Rohirrim to help defend his city; Faramir dragging Frodo to Minas Tirith to give the ring to his father; Gandalf stating that Theoden led his people into a trap in Helms Deep and only Aragorn could save them all; and so on.
Bottom line, no one in the movies could make a good decision except for the members of the fellowship. Heck, the Rohirrim would never have come to Minas Tirith if not because of a hobbit snuck past the guards. Watching that scene I couldn't help thinking of certain beholders being suckered by a thrown rock...
I know many people love the movies and I won't argue the point - to each their own. For myself, the less Jackson has a hand in the writing, the more confident I'll be. As with the trilogy, I'll wait and see.