It is, essentially, a comic book made into a movie; I doubt very seriously that the Spartans had leather speedo's as a uniform, and had a average bodyfat index of less than 1%.
The main thing that bothered me was their treatment of female spartans; they went to a little effort in showing that the spartan women had more liberties than the average, but didn't show that they received combat training.
One benefit was quickly evident, though; right after taking my 14 & 16 year olds to see it, they were fighting, literally, over my "The Peloponnesian War" books; if interest holds long, maybe I can hook them on "the 10,000".