Alice Brady is ideally cast as a temperamental diva. She is believable and hilarious. The voice with which she sings seems to be her own.
Virginia Bruce, a charming performer, is OK but no more as an ingénue.
The movie is Lawrence Tibbett's. He sings arias from several composers, as well as singing some appealing songs. (Was it common in those times for Caucasian opera singers to perform spirituals? Regardless: He sings one.) The plum is a long section of "Pagliaci," in which he is, of course, superb.
This is the only commercial movie in which I've seen Tibbett. He appears a bit stodgy and is certainly not conventionally handsome. But his singing is glorious; and singing is what this movie is about.about.