This old musical still works all right as light entertainment, although it's certainly not nearly as spectacular as it apparently seemed to be in its own time. It has likable characters and a story with just enough to keep your attention, which make up for the often creaky pace, bad dialogue, and routine acting. It's also worth watching for Bessie Love, who gives a good performance as an endearing older sister character, which in most places still holds up pretty well.
Because sound movies were still a novelty, it's loaded with singing and dancing numbers that probably seemed impressive to its original audiences. Some of them are still entertaining, while others really just slow things down. For the most part, the script is bad and the acting (aside from Love) is pretty routine, both of which stand out much more now. For example, there is a stretch in the middle of the movie where the characters have essentially the same conversation several times in a row. You still like the characters, but only Love makes hers fully lifelike and sympathetic, at least whenever the weak script gives her any chance to do so. The overall effectiveness of the movie has faded, just as most of today's flashy but empty movies will look dull in 75 years. But at least "Broadway Melody" will probably hold up a little better over time, because it has an innocent energy that most such films today lack.
So, while it is only going to be of interest to those of us who already enjoy older movies, "Broadway Melody" is still decent light entertainment that is mostly pleasant to watch. There are many better films from the era, but if you like old movies and you're looking for something to do for an hour and a half, you could do a lot worse, too.