You can tell it to do dialogue heavy stories, which helps a little, and tell it to rewrite what it just write to have more dialogue. Ultimately it's a very limited tool for fiction writing I've found.

I've had success with some promopts but for others it just falls into vague nonsense like "In a flashback a hero fights a villain." Telling it to come up with some more specific than "a bad guy" often doesn't work.