The movie kept close to the book; the characters were more believable; acting and special effects were much better; and the vampires were a little "warmer" looking, as opposed to be so chalky and "dead".
I have read all four of the books, and have watched the first movie numerous times. Each of the books is well over five or six hundred pages so you can only squeeze so much into a two hour movie. I think they did very well in accomplishing this with New Moon. The movie captured many of the key elements of the book, although many things were changed, which is expected when a book is made into a movie. My first viewing of the movie was at 12:01am on Friday and it was difficult to watch with so many screaming young girls. I saw it a second time on Friday afternoon and was able to truly enjoy it; so much that I will more than likely see it a third time.