Most reviews I've read on the movie have been laden either with misplaced criticism (dude, it's Frank Miller, what the hell did you expect?) or immature acclaim (sure, cheesy lines make funny macros, but there's a point where replicating the punchline just becomes painfully unfunny). But there's a point of view I've yet to see addressed anywhere: the way in which both the graphic novel and the movie were keeping in with the fashion in which history was related in the days of the Antiquity. Where an entertaining and/or inspiring story came first and the facts followed loosely behind, if at all.
In that respect, the movie worked brilliantly. I knew what I went in for (~2h of half naked sweaty men hacking up limbs), and got my money's worth.
One of the few things that I didn't enjoy were Xerxes' digitally enhanced voice. Not sexy. And some of the speeches meant to anvil in political agenda to the modern viewer (the Queen's speech in front of the council) just weren't very convincing rhetoric. Of course, it wasn't the rhetoric that swayed the counsil.
But over all, A+: would snicker at "mysticism and tyranny" again.