It is, perhaps, the best trailer I have ever seen.
The Sin City movie was another adaptation of Frank Miller's distinctive work. The Sin City flick was really well done and stayed true to Miller's visual/artistic style, and 300 does as well.. but in a different way.
At any rate, I haven't even seen 300 yet and I'm already looking forward to Zack Snyder (the director) taking on the Watchmen & Rainbow Six projects. That's how good this trailer is. heh.
The movie comes out March 9th, 2007.