I remember arguing in defense of God Snyder in regards to the Persians being portrayed as otherworldly monsters...that the framing device is a Spartan legend being used to inspire fighters, thus portraying them as monsters from far away, the traitor as a hunchback, ignoring the non-Spartan fighters, and so on is all appropriate and arguably "historically accurate" within the context.
The film wasting all that time with the McNulty/Queen subplot that's not from the comic probably should have been a warning about Snyder too.