The teenage goth girl who sold me and my brother tickets for this told us that it was the best movie she had seen since The Matrix. Turns out I agree with her more than I do with the film's critics, who seem to be in two camps: (1) the folks who don't like the movie because it's politically irresponsible and reactionary and (2) the folks who don't like the movie because it feels like a big, stylized video game.
My Take: that's all true enough, but, to me at least, it seemed like everything was in quotes. This is a "Pro-War" movie and there's lots of "Violence". Everything is aestheticized though to such an extent that my reaction was basically to nod along in appreciation of the choreography, the realization of Frank Miller's images, and the physiques on display.
What made me like it rather than just be impressed by it, is that it didn't feel pushy at all. On the one hand, this meant that I never really got caught up in it or had much in the way of an emotional reaction. On the other hand, it meant that I could sit back and enjoy it without feeling worked over.
I want to see Sin City again - I caught it on its opening weekend and was done in by its length, despite liking parts of it quite a bit - but what I like about 300 is that, unlike Sin City, it isn't obsessively concerned with recreating Frank Miller's images on the screen almost exactly as they appear on the page. That seemed to not only have the intended effect of flattening everything out, but also the unintended effect of being kind of redundant. And fetishizing the images seemed to take the life out of them: their pulpy charm was undermined by the millions of dollars spent to "bring them to life". However, 300 treats its source material slightly less reverently: Snyder and his crew conceive of everything in terms of space, movement, and depth. It's still like the space, movement, and depth in a video game, but there are still moments of brainless blockbuster poetry (I'm thinking specifically of the two bits dealing with walls of bodies and the first slo-mo/heavy metal sequence).
My Even Quicker Take: Yes, it is like a video game, but it gets by because it has a sense of assuredness and willingness to slow down and stand back. I think it's a lot like Hero or The Promise, the difference being that wuxia is still kind of a living B-movie genre, while Sword & Sandal is a thing of the past. Still, the formula is the same: all these movies build elaborate, spectacular, action set-pieces out of the standard B-movie tropes that grew out of economic necessity. (Hero probably goes over better with critics because of its foreign art house pedigree).
See also: Sean Collins and Jim Treacher on 300.