Frank Miller didn't direct the movie, so who cares.
Yes he has done some less than fantastic projects, but he has also done some extremely good ones. Sin City turned out rather well I think, there is some hope that this might too.
Incidentially, there is no 'American' perspective to the 300 story. American military historians have a soft spot for ancient Grece, but I have a hard time seeing the story as analogous to anything contemporary.