Hmmm...Kyle Smith of the New York Post thinks the movie could have easily been used as a Nazi training film:

But keeping in mind Slate's Mickey Kaus' Hitler Rule - never compare anything to Hitler - it isn't a stretch to imagine Adolf's boys at a "300" screening, heil-fiving each other throughout and then lining up to see it again.

Gosh, that seems a little harsh. This comes at the end of the review, so how is he justifying such remarks? Earlier he says:

Leo frames his struggle as a war against barbarism, but his is a "culture" that puts babies to the sword for looking like weaklings. He ignores both religious counsel - a half-naked oracle chick who delivers her messages via writhing performance art - and Spartan law, seemingly because he views death as a promotion.

Even the softer voice of Leo's wife (Lena Headey) tells him not, "Pick up a gallon of milk on your way back" but "Come back with your shield or on it." Like "no prisoners," which also pops up here, this is a familiar battle cry that makes no sense unless violence is war's goal rather than its means.

So our "hero" is a psycho, which puts a hollow at the center of the story. But can't we just ignore the politics and enjoy the decapitations?

So killing unwanted children gets you quotation marks around "culture"? Hmm, what other cultures might have practiced euthanizing children? I wonder...

And I can't say I have a problem with ignoring religious counsel. How about he ignored the advice because he knew it was crap? The priests were lackies of the Persians, and (spoiler warning) so was at least one member of the counsel.

And as far as taking no prisoners, how about they didn't have the logistical capability to hold or guard prisoners, since they numbered in the thousands and were fighting in a narrow, rocky pass? Um, duh.

And a Nazi propaganda film? Yes, the movie lovingly visualizes violence, but I don't think it's mindless or in promotion of dictatorship. In fact it's the opposite. Xerxes is analog to Hitler, sweeping across the world and consuming everything in his path. Hiding behind the lines and sending waves of soldiers to die.

I guess in Smith's version of the film (and I guess history), Leonides would have just bowed down and kissed the messengers hand, turned over his lands to Xerxes, and the whole thing could have been over in 5 minutes.