Claude Rains did not receive an Oscar nomination for portraying Erique Claudin the titular character of Phantom of the Opera.
I say almost every character is dull because there is just one character who is not played by the always competent Mr. Rains. This version of the phantom begins as a violinist at the Paris Opera house. He is a career performer who finds his talent fading when he begins to suffer a physical ailment in his hand. He is fired, and has no money because he has funded the musical training of the young singer Christine. Rains is really good in these early scenes at being just a sympathetic fellow. He is so unassuming but charming, and the scene where he plays his lullaby is beautiful as Rains reflects the love Claudin has for his art. He shows that he is a perfectly honest man who and his helping of Christine is entirely pure.
Rains makes us feel sorry for Claudin effectively, and honestly I think I would have preferred if this film followed the musician down an inspiring path. This is not the case as Rains returns to his Universal monster roots in this film after Claudin finds a man is trying to steal his music which results in him killing the man, and someone else scarring him with acid. This is all probably a bit too sudden for its own good making it so Rains has to turn up to 11 a little too fast. He does as well as he probably could in portraying the sudden insanity in Claudin because he set up how passionate Claudin was about the music. It still seems a bit too far, but Rains does not fail in this despite the extreme limitations put upon him by the story.
Once he becomes the Phantom we don't see all that much of Rains and not just because he is wearing a mask. The film is too busy spending time with the downright boring characters. When Rains does show up he manages to lighten up the picture a bit with the energetic evil he has in the role of Phantom, although even this is a bit limited since the film spends very little time with his villainous deeds. He gets to do more in the climax of the film when the Phantom kidnaps Christine. The film fails in that it did not create a pseudo romantic, or even mentor type relationship between the two beforehand, but Rains gives it the good old Thespis try to make up for the film's inadequacies.
In the climax Rains tries hard to bring some conviction to his part, and does have one very good scene when he plays the piano with Christie singing. Rains's expression of sheer glee is a pretty brilliant way of showing how Claudin's pure love for music has turned into the phantom's deranged perverse obsession. Anyway this far too short scene is interrupted by Christine removing his mask. Rains is rather moving once again seeing the defeated Phantom with nothing left, and makes him the tragic figure he should be. The film again quickly ends as there is a cave in and the Phantom appears to have died. Rains is lead, but very limited by the grasp of the film. Rains does give a solid performance through the little he has, and is easily the best part of the film even though that is not saying all that much.