I'm not into violent movies but I've just watched 300. I fell asleep while watching the Lord of the Ring movies but I didn't even blink for a second when watching 300.
300 is not the best movie I ever seen. However, I must say that it is the most visually eye-popping experience I ever had since Jurassic Park. The bloody battles and beheading scenes were very impressive.
I don't think 300 is historically accurate but who cares when you are watching great acting skills from Gerard Butler as King Leonidas and Lena Heady as the Queen who fights for the freedom of their country.