Podcasts certainly have their worth. There are many, many remarkable shows like 99% Invisible, Akimbo, This American Life, Revisionist History, and Longform. What podcasts offer uniquely that books can’t is wide exposure and a deep sense of humanity that comes from sometimes intimate conversation. Podcasts, in other words, offer a breadth and diversity that most books simply can’t compete with.
Books, on the other hand, offer depth that blows podcasts out of the water. If you’re trying to be a better writer, you’ll be much better off reading a highly recommended book on it than listening to a podcast episode about it.
If you’re looking for exposure, listen to great podcasts. If you’re looking for a deep dive into particular topics, check out books.