As I understand the movie is based on a real event, and is some what accurate.

Its been shot in front of a blue screen, so a lot of effects can be added latter on, and a lot were, from the weather to massive army’s.
I don’t want to give too much away, but its a movie about how 300(ish) Spartans held off 150,000 Persians for about 3 days.
The movie has lots of blood in it, so just keep that in mind when you are choosing if you want to see it.

I found its style a bit hard to get into at first, but soon found it rather compelling.
I’m not sure I would go straight to “I enjoyed it”, but, yeah, its up there with some of the more interesting movies I have seen…..its pretty memorable.