Well, I'm supposed to be doing summer homework (there's an oxymoron for ya) and I'm shirking as usual, so I don't have time to read the whole thread or write anything overly complex. I think the character that was the most different between the books and the movies, though, was Aragorn.
In the book, he has set out to regain his kingship and set things right in Gondor and all of Middle-earth, but in the movie he's portrayed as so reluctant. Book Aragorn is always saying things like, "I can't wait to get back to Gondor" (okay, not that exactly, but you know what I'm talking about
), whereas Movie Aragorn seems to want nothing to do with it (aside from saying "Long have I desired to look upon the kings of old, my kin" when they pass the Argonath. And speaking of the Argonath, does anyone know which is Isildur and which is Anárion?)
However, Book Aragorn is also somewhat cocky. He thinks that just because he's heir to an enormous kingdom he can boss people around... now, whatever put that idea in his head!