Have you read the book? It's not appropriate for young children, it's a very emotional and sad book. Reviews that I read this morning are saying that the movie IS closer to the book then the trailer leads you to believe (book spends little time inside the fantasy world of Terebithia while the trailer looks like it's all about that and people have been disappointed that it's not like that).
The reviews I read this morning were also saying to not bring children under 10. I am taking a group of children on Sunday and we limited the book and movie club to 3rd, 4th, and 5th graders.
It's heavy content.