Zack Snyder's 300 had a lot to live up to. Which is its own fault. Within the blitzkrieg of advertising that foreshadowed this film a lot of bold claims were made. This film will reinvent cinema! Something this kick ass hasn't been seen since The Matrix! 300 heralds a new generation of filmmaking! Your eyeballs will bleed from an inability to cope with the awesomeness contained within 300!
If filming every scene in front of a green screen and in either slow-motion or fast-forward is revolutionary, then we're in for a lot of crappy films from people trying to be as good as Zack Snyder.
You will be entertained. That is if you crave violence and amazing battle scenes. Otherwise, there isn't much else. There are even 3 decapitations in this film! All of them in slow motion with extreme close-ups. The battle choreography and storytelling ability of Mr. Snyder is overwhelming. Every second of the film draws you in. The escalation in drama is palpable. All of this can be contributed to the amazing green screen effects and the gory slow and fast motion battle scenes. None of this can be contributed to the writing.
I haven't read the Frank Miller graphic novel, so I don't know how much of this can be contributed to Mr. Snyder or Mr. Miller, but it's pretty dry. The actors do their best with it, but it's fortunate for the viewer that the film does not dally with conversation much. There is one point in the film where the king's wife must do something very drastic in order to "save her kingdom." However, there is nothing in the dialogue leading up to this event that would warrant it. It somehow just happens and then the viewer is left with a much lowered regard for her character and the workings of the Spartan government.
There isn't much else to say. This is a great movie. It is raw entertainment. It is not as revolutionary as The Matrix in regards to story or film innovation, but it is just as enjoyable. See it on the big screen, because when it comes to a movie like this, bigger is much much better.