The scene with Simon on the bridge
with him whimpering and yelling "I'm sorry" is one of the saddest scenes in a movie I have ever seen. You can't help but feel the shock and misery of what has happened to him and the great sense of loss. You just want to run to him and pick up and take it all away. It is such an emotionally effective scene.
And also, I have read 'A Prayer for Owen Meany' and obviously saw the movie and I enjoyed them both. I liked this adaptation and think it worked in the amount of time generally available in a movie so I don't understand all of these people who are so bothered that it doesn't 100% fit the book... They never do. But props to the movie makers for capturing the spirit of Owen Meany in Simon Birch.