But let him know that he may enjoy it the second time better than he did the first time.
My first time through I enjoyed it, but was nerve-wracked worrying whether every scene would be right. And noting every difference in the story.
The second time, of them all, was my favorite view. Gone was my worry that Jackson wouldn't do it right. I could sit back and let him tell the story his way, and marvel in the beauty of it - and he really does a beautifull job telling the story in just three hours.
Are there changes? - yes. Are lines moved around and characters omitted and events changed slightly? - Yes. But only to make the story fit onto film. And changes were done with caution and care. Do I love all of it equally? - No I suppose not, but parts of it are so perfect I am still brought to tears.
Trust me, brother of MozartLover, if you don't trust your sister, which you should. This movie will captivate you, it will do justice to your story, the movie loves the book, and it will draw you in and break your heart the way the book does.
For Pete's sake, in the time you spent yesterday arguing about it with you sister, you could have just let her take you to see it. You would have wanted to go again by today.
ML - go to ecurbh's trailer page and download some of the trailers. (best is Theatrical Trailer 3) but all of them show different scenes that will convince him. Let him watch those!