Audible is a okay app and a great service. I have used it on and off for year, mostly on over the last 2-3 years. I listen to a lot of audiobooks. My focus is to try to listen more to them than podcasts. I'm on a annual 24 credits a year plan. And I usually listen to more than 24 books a year.
Over the last few years they have started to add more and more free content with the memberships.