Adapted from a graphic novel that condenses the two battles of Thermopylae into one. Leonidas of Sparta vows to stop the Persian king Xerxes' advance and conquest of Greece. He leads 300 of his most loyal men to certain death against the Persian's far superior numbers.
Told as a flashback by the lone survivor, the film has taken a lot of negative feedback for its simplicity and cliched dialog. What they don't take into account, or wrongly attribute to the graphic novel source, is that cliches start somewhere, and this language is coming from a pretty ancient source. Spartans were not known for their eloquent turn of phrase.
The point is, this is an action movie. Dialog doesn't move the plot. It just explains how we got to the fight scene. And the fight scenes are excellent. Full of blood, sweat and testosterone, loyalty, daring, power and grace. There's no small amount of gore, but it's part of the larger theme.
For those who like this type of movie, it's one of the best of its kind. For those who don't... this is not the film for you.