Film adaptations of stage musicals are a tricky business. Adhere too closely to the stage show and you lose sight of the possibilities of the cinematic medium. Stray too far from stage roots and the necessary suspension of disbelief becomes impossible.
I think the best example of a perfect melding of stage and screen is Chicago. All the advantages of being a film are there: big sets, immersive environments. All the advantages of being a stage show are also there: the production numbers, the knowledge that it’s not a pure story – people don’t just suddenly burst into song in the middle of real life.
Phantom couldn’t find that happy medium. In fact, at times it had trouble deciding whether it was an opera, a musical, or a movie. For whatever reason you never sympathized with the characters or their predicament. I think the filmmakers tried to do a pure adaptation: take a stage show and put it up on screen. You’ll find though, that the screen is a good bit smaller than the stage, it’s easily overwhelmed. That might have been the biggest problem.