I'll be in a minority here, but as someone who doesn't like Twilight and someone who intensely disliked book!Bella I actually very much enjoyed Kristen's Schauspielen and the way she portrayed her heroine, I thought she added some depth to her character and made her less whiny and Mehr dramatic/romantic, thoughtful, sad, I don't know... there was something about her Bella that made me appreciate this character in the movies.
Yes. Kristen's a great actress but most people only watch her in the Twilight films. That's why she get's so much negative cred. My Favorit film with her in it is The Runaways. I haven't gotten around to watching Snow White and the Huntsman but I heard she was very good in that film, too.