FearNet has up an article talking about the 20 main differences between the New Moon movie and book and why they work.
Here are some of my personal favorites from the list:
Way more shirtless boys!
We all hoped to get a glimpse of Edward's alabaster chest in Volterra, but who knew we'd get to see so much hot werewolf skin? Thankfully, the Wolf Pack run such high temperatures and explode away their clothes so frequently that cut-off jeans and no shirt are their shared ensemble of choice.<----YESSSSS!
Jacob gives Bella a dream catcher.
One new scene in the film has Jacob giving Bella a dream catcher for her birthday, killing two birds with one stone in the process: giving her a present when Edward feels he cannot and putting the mack on her with a big bear hug right in front of Edward. Bella hangs the dream catcher above her pillow, but unfortunately for her, it doesn't help keep the nightmares away.
Two words: Face Punch!
In addition to the zombie genre, New Moon has a little something to say about stupid action flicks. One of the best additions to the script involves Bella, Mike Newton, Jacob, and a popular (fake) blockbuster movie entitled Face Punch. (Tagline: "Let's DO this!")
Bella hits Paul in the face!
In a film packed with phasing wolves and marble-cracking vampire fights, it's nice to see Bella get a little action. Angry that they've brainwashed her beloved Jacob, Bella confronts the Wolf Pack, shoves Sam Uley, and smacks Paul right in the kisser! Sure, it seems a little out of character, but at least in this moment, Bella is an agent of action and not merely reacting to the people around her. Plus, it leads into Paul's transformation and Jacob's mid-air phase, and the huge revelation of the Quileute secret.
Jacob and Bella almost kiss. Twice!
New Moon is Jacob's movie, so Rosenberg rewards him with not one, but two almost-kisses. If you look closely, their lips ACTUALLY TOUCH the second time!
Jacob and Edward face off in the woods – just not when you expect.
If you've read New Moon, you're already expecting the tense "treaty" discussion between Jacob and Edward. Rosenberg wisely juggles the timeline a bit, placing it before the key conclusion (see #19), and adds one last phase for the furious Jacob. (It's the closest Bella's two men come to blows in New Moon.)
Yeah, yeah, yeah, I know they are all about the wolf pack but I don't care! :)