I saw this last night on the IMAX with two guys who had already seen it on a regular screen.
The movie is good, the battle scenese are fantastic and the cinematography is ASTOUNDING.
It's the story of 300 Spartans fighting of the invasion of the Persian Empire, but you don't really have to know too much to to enjoy or get the flick.
I think anyone with a drop of testosterone in their blood will enjoy it, and my girlfriend said the shirtless Spartan warriors made it pretty easy for her to sit through (there's a couple nice Spartan gals, too). The extra $3 to see it on the IMAX screen was also well worth it.