Not saying it needs to be 100% faithful or even close to it, but even leaving aside the books you still need to get the pacing right and have something that resembles an arc for the film itself. Instead we got the horrible Star Wars method of story telling. But in a two part film I don't think they had much option.
LotR is a great example, the pacing and structure of the first film is superb, but they're only able to do that because the book itself is full of a load of garbage that's easy to cut away and the book is generally is slower paced, so it translates lot better.
