Boxofficeprophets has a well-considered article by Kim Hollis that looks at the differences between Daniel Wallace’s book and the movie version of Big Fish:
John August’s screenplay does take great liberties with the story detailed in the novel. Much is added or embellished, which is almost necessary given the brevity of the book. None of the expansion feels forced or off, though. It’s perfectly in keeping with the story of a man whose life was truly monumental.
You can read the rest here.
Thanks to Daniel for the forward.