I finally gave into curiousity and went to see "300". I enjoyed the movie - and I'll accord it the rate or 'worth seeing'.
Some have written - and correctly so - that "300" completely omits that the the Spartan's held sway by force over the Helots with whom they shared region of Lacedaemonia and thereabouts. Then again, everyone had slaves. The Athenians used slave labour to mine the silver mines that paid for its naval might. We should hence overlook this - as the film is about the awakening in man of the spirit of freedom, free will and independance from tyrants. It doesn't mean that it was immediately perfect. There's no reason to judge those Spartan's on the basis that they had what amounted to slaves.
The film does a good job in explaining the Spartan's hoplite phalanx-based method of conducting warfare. On the other hand, I remember reading that Spartan's fought barefoot - whereas other Greeks generally wore sandals in battle. It seemend that all the Greeks were shod in sandals in the battle scenes. Some of the Spartans wore a beardbut no moustache - but more had a full set of hair on the upper lip, or were clean shaven.
The film is purposely dark and somewhat grainy. It seems perpetually to be dusk. War is a dark subject - so perhaps the producers thought that even one ray of sun would break the mood.