Gerard is a worse singer but is the better actor. At least he could have emotional moments that were good, though his terrible singing really ruined it. Emmy's voice was slightly above average but nothing special. Her acting is terrible in this role. She doesn't seemed tortured by the Phantom but instead emotionless or having a dumb little smile on her face.

^What KataraLover said, though i do think Rossum's voice was slightly worse than Butler's. Though to be fair, I guess her voice has improved... in the same way that a C is an improvement over an F...
Also, her underacting irritates me to no end and does not complement Gerard's overacting in this movie. It's ironic, because Gerard doesn't overact in anything else. I guess he felt like he had to over-compensate for his horrible singing and the godawful quality of the movie overall.

Also, isn't Christine supposed to be beautiful?

^ Emmy is beautiful, imo.

I honestly thought Gerard Butler's singing was awful and it ruined the whole movie for me.