Tell it to do upbeat electro pop and it is already excellent. Jazz and Metal, not so much. If it improves at the same rate midjourney did at images, however, it will make new bands entirely redundant within a couple of years. The influence of this will be utterly massive. The way I can see it being used is in giving people music as they want it
Hey Alexa, play me Morbid Tales-era Celtic Frost with Master of Puppets Hetfield singing
Play me Back in Black with Bon Scott singing
Play me sad xmas piano ballads with Morrissey singing
Play me lots of catchy pop like "Can't Get You Out of My Head" all sung by Grace Jones
That kind of thing. It is end times for bands because, let's be honest, the discerning music lover is very much a niche item. Most of the public don't give a sheet where their music comes from, or that it was composed or played by humans.