I was worried that the movie wouldn't be able to stay true to the book, as I'm sure every Twilight fan was. I was also afraid that the actors wouldn't be able to fulfill their roles. All my worrying was for naught though. This film, and all the actors were directly in tune with Meyer's novel.
I will warn you that if you're a diehard Twilight fact-checker, you'll probably be disappointed. Some stuff was moved around to make sense in a movie setting, and they reworded the heroin line. But the movie did catch the personality of the book, and completely did it justice.