I saw it twice, actually.
I really don't think it would be possible to show the Spartans at all accurately without showing some of the "neocon" elements. They were very into the glory of war; their whole culture was built on it. (And, not to put to fine a point on it, the Athenians were boy-lovers. It was a major aspect of Athenian culture.) The description of how the boys were taken away to be trained is pretty accurate. Sparta was a warrior society; to portray it as anything else would be to show a different culture.
Now, it's not my era; most of what I know about Greece has to do with its mythology and architecture. However, I know that, for example, it was considered one of those regular things for an Athenian to, er, introduce a teenage boy (or younger) into sexual activity. I know that the Spartan culture was built on training for war, and that the greatest love in all Greek societies of the era was the love between two men. (There, that's homophobia and homoeroticism out of the way; both of the attitudes are accurate descriptions of the time and have nothing to do with the judgements our society would impose.)
I know that the rhinoceros was just plain silly. I know that "freedom isn't free" is a much older sentiment than we realize, but that "freedom" would be a relative term in an era with so much slavery. I know that the movie only dabbled in the relative equality (that's relative to other women of the era, of course) of Spartan women.
However, I have noticed that quite a lot of movies serve as Rorschach tests; what you see in it is quite often what's in your head rather than what's on the screen.
"Now everyone was giving her that kind of look UFOlogists get when they suddenly say, 'Hey, if you shade your eyes you can see it is just a flock of geese after all.'"
"You can't erase icing."
"I can't believe it doesn't work! I found it on the internet, man!"