I would wager that just about anyone reading this who might want to see 300 already has done so. Nevertheless, my impressions:
It's the story of the Battle of Thermopylae, where a small and
disciplined band of Spartans went up against the massive Persian
(The movie refers to the battle taking place at the "Hot Gates". Many
hours afterward, I made the connection to "Thermopylae." Duh.)
Based on a
comic book graphic novel
by Frank Miller, it has distinctive and spectacular visuals.
It also has a distinctive point of view, with the Spartan good guys
on the side of freedom, justice, and reason, happily sacrificing their
lives for in the service of the polity that supports such goals. And
they have impressively large muscles.
The bad-guy Persians, on the other hand, represent mysticism and slavery. Worse, a lot of them sexually ambiguous, perverted, or monstrous.
Couple all this with a number of Spartans that are less than loyal to their side, and see nothing wrong with taking some gold from the Persians in order to subvert and delay effective action on the home front.
Not surprisingly, this irked some whiny lefties, and even got poor marks from the foreign reviewers. As a remedy, and a guide to what's real and what's fake about the movie, Victor Davis Hanson is your guy, probably best to be read after you see the film.
Bottom line: it's a lot of impressive fun, and worth seeing for anyone not put off by (as the MPAA says) "graphic battle sequences throughout, some sexuality and nudity."