I really liked it! Charlize Theron absolutely MAKES the film, when she's not on screen you find yourself wanting to get back to the castle and see what she's up to; some people have said that she goes over-the-top with her performance but I thought it was easily the best in the film (despite a few little accent slip ups). She is also glowingly gorgeous in this film!
Kristen Stewart surprised me - I haven't seen any of the Twilight's but people bash her acting quite a lot - she's solid throughout the film, and her English accent is very good.
Overall I'd recommend it; if you've seen the trailer and liked it then you'll like the film, the trailer really puts it across well.