Frankly Lord of the Rings should have been broken up into six movies for the six books. Rather than three movies for the three volumes.
Jackson practically skipped the entire first book in "The Fellowship of the Ring". Such as the seventeen years that passed while Frodo had the ring and still lived in the Shire. You got no feel for this in the movie it seemed like it was a couple days. Everything involving Tom Bombadil was cut out. End Farmer Maggot was a brief antagonist in the movie while he was a friend that aided Frodo and the others in the book.
Of course everything regarding Saruman taking over the Shire and the Hobbits defeating him and his remaining forces was cut from "The Return of the King".
I have to say that I actually liked TLOTR movie adaptations and thought they were surprisingly good and well worth watching; most of the time, I absolutely hate it when books I have liked or loved have been transposed to the Big Screen (the Small Screen, with British TV, tends to be a good bit better where faithfulness to an original text in concerned).
In general, though, my heart sinks when I learn that a movie adaptation of a well-loved text is contemplated; usually, this means obscenely good-looking actors, along with a total disregard of context, plot, nuance, narrative, actual text, and spirit of the work, (and often, even worse, an altered - i.e. more 'upbeat' ending, too) in order to fashion a banal, clichéd, trite, offering which hopes to cash in on the success of the original.
The movie adaptations of TLOTR didn't do that; sure, they took short cuts, but was broadly faithful in tone and content to the original, and the whole thing was beautifully filmed, as well.
In any case, I've always liked The Hobbit - and it will be interesting to see what is made of it by PJ.