Yup. The biggest change was in the chapter Riddles in the Dark. When Tolkien wrote The Hobbit, he didn't have any of the original ideas he had for Lord of the Rings. Gandalf mysteriously disappeared because he was just a sort of mentor character. He saved everyone's butts once, but couldn't be a crutch. Indeed, his absence is what forces Bilbo later on to "nut up or shut up".
I feel like making The Hobbit into two movies isn't being done in any way to actually honor Tolkien's creation with an accurate book-to-film translation. It's partly for the money, and partly, at this point, just a vanity project of Peter Jackson's. The Hobbit shouldn't be, thematically at least, at all like Lord of the Rings. It ruins the nature of the story.
But I'm a pretentious wet blanket. As I said, I'll still see the movie.