The teller of tall tales takes on a tough task (besides risking too much alliteration). The tales have to be exceptionally creative, because they are supposed to surprise and delight. But their fabulist nature also makes it more difficult to affect the audience emotionally. The audience knows the stories are fake and thus have no anchor in real human need and motivation.
Tall tales also tend to become highly episodic. Made up of bizarre and outlandish events, they highlight a moment or a single image instead of a steadily building web of cause-and-effect.
Big Fish doesn't know how to solve the unique problems of the tall tale. It's a patchwork script, and its attempts at solutions just make the problems worse.
The writer tries to affect the audience emotionally by framing the fantasy story with a son's attempt to get close to his storytelling father. This line is psychologically real but boring in its execution. It also feels like much ado about nothing. So what if dad likes to make up stories and repeat them a few too many times.
What's worse, this technique of a second, realistic story line backfires. Instead of anchoring the tall tales in some recognizable human emotion, the realistic line cross cut with the fantastical line seems like two different movies stuck together, and neither is done well.
An even more serious flaw with this script is that the tall tales aren't that delightful. This is where the fantasy game is won or lost. In Big Fish we have a giant who doesn't do much, a big fish, and a parachute drop behind enemy lines where the hero encounters a woman with two heads.
There is a Utopian town, which is quite common in fantasy and can be very powerful. But this town is never explained or given any larger symbolic meaning.
The first lesson here is simple. If you are going to do tall tales, do them all the way. You're in the fantasy genre, and once you get the audience in its own fantastical world, you have to keep them there.
In the Fantasy Class, I talk about the fact that fantasy is more dependent on the premise set up than any other form. If you don't get in and out of the fantasy properly, you can't build the fantasy and you can't make the necessary emotional connection between the fantasy events and the characters' psychology in the real world.
The second lesson is: once your audience is in the fantasy world, you better tell the most imaginative tall tales anyone has ever seen. Great fantasy is about showing people possibilities they never even dreamed of. That's a high standard, but in this form it's the only one that really matters.