I'm pretty sure they just made this movie as an excuse to have fun. The character arcs are meaningless, it doesn't have a lot to say about anything... But don't take my first assumption as a criticism: this movie is tons of fun! The comedy is hilarious, satirizing the star system and the transition from silent films to talkies, the music numbers, while i don't think every song is as memorable as the title one, the passion they put into every number is contagious. It is weird, though, that on a movie asking for respect towards the people who do the dubbing of famous actors, they dubbed Debbie Reynolds for some scenes and didn't credit the actress who did it, Betty Noyes.