Lord of the Rings Trailers
Just to re-live the sheer action difference between artistic prose (which is somewhat boring) compared to high-speed moviemaking that would soemtimes sacrifice some fans to get different fans.
www.youtube.com/watch
www.youtube.com/watch
www.youtube.com/watch
And if this adaption has not come to life (one of the most faithful adoptions to anything IMHO), I wouldn't have bothered to read the books.
On a few nitpickings against fellow critics:
Boromir is not one-dimentional. He never had the time to develop, and we never had the chance to know more of the noble older brother that loved his people (and was quite cynic about it.)
Aragorn is almost one-dimentional, but that can be attributed to his lack of non-combatant contributing in the script. He was a man destined to greatness, and he fulfilled all he wanted and more, and not through sheer authorial love.
Saruman is not one-dimentional. He had potential, but our POV never allowed us to understand him.
Legolas is not one-dimentional. His role in the movies undermine his role in the lore. He's a good person (elf?) who manages to overcome eon-old racism and make friends with Gimli. Though admittingly they both needed more personal screen time, yet it would probably be on the story's account.
Arwen is not one-dimentional. Her story is quite tragic and she's not only a love interest. I understand people feeling robbed when Glorfindel was replaced, but her character demanded more screen time and I see it quite (if not wholly) justified.
I think that if Lord of the Rings was bigger than it is, it would probably flesh out all the rest. One can observe that the more screen time Tolkien assigned to a character developed that character, as with Frodo, Sam and Gandalf as examples.