Just saw the movie. Great action scenes, some of the best I have seen so far. One scene that took my fancy was the one where these words are uttered by Leonidas in response to a threat by the Persians to black out the sky with arrows: "Good, then we shall have our battle in the shade...," or words to that effect.
On the other hand, the overall feeling I got was that the movie is being used to send a message to the Iranians. Right wing talk radio has already recommended it for an Oscar (claiming that if Al Gore took one for the Dems, '300' should take it for the Reps. Good to see them embrace Hollywood for once. BTW, the heroes -- Spartans-- look incredibly Anglosaxon while the bad guys -- Persians-- look very dark skinned. Coincidence?)
So to me, the movie is a modern equivalent to the WW2 movies called "Why we Fight" that were produced for one purpose and one purpose only: Propaganda.
http://en.wikipedia.org/wiki/Why_We_Fight
Although -- as a collegue pointed out --the Persians seem to represent in military terms, all the US does in the 21st century.
But then, what does he know?