Well, you're judging her by one film and that's not very fair. You should at least see The Heart is Deceitful..., B.Monkey, The Stendhal Syndrome, Scarlet Diva, or Dario Argento's Phantom of the Opera. Any of her movies, really.
I know this is late, but it's been bothering me. XXX shouldn't be used as a measure of anyone's acting. It was a popcorn movie and Asia was underused anyway; just like in Land of the Dead. No one should be judged by one movie; that's just stupid.