I loved this film. On the surface, it is about a young man, William, who is estranged from his father, Edward Bloom, because of the latter's long absences from home and unbelievable stories he tells. As his father is dying, William tries to come to terms with who his father is, and realises that he cannot separate fact from fantasy so easily. His father was defined by the stories he told, and the son can only truly accept his father by accepting this and entering into his world of fantasy.
This is why the film may seem bizarre, even surreal, as we are drawn into Edward Bloom's fantasies and entertained by them, even while realising their impossibility, as the son does. Our scepticism is put on hold by the end, as we begin to accept the improbable and impossible, and we too are charmed by the stories that are Edward Bloom.
It is, of course, a metaphor for the human condition and consciousness, in which we are no more or less than the stories we tell about ourselves.