Emmy Rossum is an absolutely horrible actress! She is one of the worst I've EVER seen, and not just in this movie (watch Genius, The Day After Tomorrow, Dare, Poseidon, and Nola to see what I mean; she's awful and literally has given NO good performances in any of her films). She's like a worse version of Kristen Stewart's performance as Bella Swan (which I didn't know was possible). She has ZERO charisma/screen presence, she made the flat character even flatter than she is already, she has like one facial expression throughout the whole thing, and she makes the character even more annoying with her horrid acting. Don't even get me started on her abhorrent singing, or the creepiness that is her being 16/17 when filming while Gerard and Patrick were in their late 20's/early-mid 30's.

Though the movie would still be horrible, Kate Winslet would've been the perfect choice for Christine in the movie and would've attracted more of an audience. She would be able to embody what they wanted Christine to be but also someone who could actually act, had charisma, and have realistic expressions and mannerisms. Plus, link. Oh, and casting Kate Winslet would've made it less creepy since she's wasn't underage (like Emmy was).

More examples of Kate Winslet's lovely singing voice:
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You got this idea from my Sophie Lowe poll, didn't you? lol

Anyway, BY FAR! Kate can actually act, is a MUCH better singer (Not sure if it's right for Christine), and is gorgeous. If it was only The Phantom that was much older than Emmy, that would be okay because he is supposed to also remind her of her father and would just add to the creepiness of his obsession with her but it is weird that Raoul was played by an actor that was thirteen years older than Emmy. That would not fly if this was being made today and they tried to do the same (Although, if they wanted a 16-year-old to play Christine, Jackie Evancho would've been the perfect choice for that).

Emmy seems to do the opposite of what Sierra Boggess was able to do with the character of Christine. Sierra actually made the character interesting with not only her amazing singing but also her acting. She makes me be on her side and get invested in her because she really sells her fear of feeling like The Phantom is always watching her and she has no escape. She even adds more personality to an otherwise bland and flat character. Emmy just seems to make the character worse.

To be honest, Emmy was probably directed to be the way she is, and I don't understand why Schumacher or Andrew Lloyd Webber thought she was a good idea. There were some... questionable casting choices in that movie, to say the least.

To be fair to Emmy, I really like her on the TV show Shameless. It just shows what wonders you can make with an actor or actress with the right director.