I'm new to this website/forum, so far I can't see any other replies/posts.
As far as how well the book/movie worked, they were different.
The screenwriter Melissa Rosenburg was asked why she had the wolves actually attack in the movie, and she said it brought more drama than just the discussion. I was in the audience at this interview, and although I had seen previews, I didn't believe the scense were showing the laPush shifters attacking the Cullens. I had thought it was some recollection of the Volturi about their fights against the Children of the Moon. This was one of the biggest differences, obviously.
Another comment (perhaps the screenwriter didn't make this one) was that the wedding was not heavily written in the book, so there was a lot of room for the toasts. And the toasts were great. They allowed more drama, and more character interaction. I think they were fun for both the Twilight fans and the more casual viewers. I did see a review in which someone commented that the movie overall would have been improved if Jessica had been allowed to just pop her head into various scenes and make a comment.
I missed having Seth inside the Cullen house. I thought those were some of the warmest scenes from the book. And of course, I missed the Jacob-Rosalie blonde joke wars. But enough about my thoughts on what I missed.
And of course, one of the biggest differences was the fact that Rosalie and Esme left Bella alone in that exam room with Carlisle and Edward. This was the dramatic scene where Bella is left alone on the exam table, after Edward stalks out of the room. It portrays her isolation beatifully. But in the book, Rosalie and Esme would NEVER have let her go into an exam alone with Carlisle and Edward, one of the two were always at Bella's side. So she wasn't alone.
Another scene that was nicely played on screen, and I don't recall from the book, was the bathroom scene when Rosalie is drawing Bella a bath, and Bella begins to drop her robe, showing her emaciated figure.
So, enough from me.