The plot of the movie is based on a comic by Frank Miller("Sin City"). The movie describes the gruesome battle of Thermopaly(480 B.C.E), in which king Leonidas and three hundred Spartan warriors fought to the death, against the enourmous Persian army, led by king Xerxes. This battle enabled the greeks to prepare to fend off the occupation attempts from the east, thus contributing to the rise of the Hellenistic and Western culture and the creation of the first Democracy in the world. The movie is full of visual and vocal effects and action.
Some critics criticize the movie, complaining that the plot is too shallow. But it is important to remember that Frank Miller wrote 300, trying to keep the story as "cool" as possible, not to be accurate historically speaking. He succeeded in doing that and "300" is considered one of the best and coolest graphic novels in the comics world. The movie should be looked at not as a documentary or some drama picture. The movie is definitely very good in its genre and considered one of the best movies of the year. (Recomended for the girls that are interested in seeing 300 men with lots of muscles :) and for all the action movie fans).