Noah dramatizes a well known biblical story with all the spare-no-expense imagery of contemporary film making. The ark size and design are both realistic and based on the bible story. Unlike most representations of the ark, the film makers considered that the ark just needed to float, not navigate, and thus it did not need to resemble a boat.
Unfortunately the film pays less attention to the narrative aspects of the source material. The bible story is concise (Genesis 6-8), so some fleshing out is to be expected. Aspects of the story are pulled from obscure sources including books of the Apocrypha, but eventually the narrative directly contradicts the bible story. This has led many Christian organizations to condemn the film, and at one popular Christian film review site the moral rating is “extremely offensive.”
Biblical authenticity aside, the decision to present Noah as the worst kind of old-testment patriarch ends up confusing the story arc, limits viewer identification, and muddles the climax. Changes to the narrative also allow more opportunities for violence. Granted, the flood had a high body count, but I was not expecting the amount of fighting and killing shown, or the violence against animals in a story about saving animals.
Ratings boards agree this film is not suitable for children, but disagree on whether there should be restrictions on children attending. In Canada, most agencies rated in PG, with only Ontario setting an age restriction with the 14A rating.