Here are my two cents:
When I became a subscriber, the app was in a working condition. Really the only thing I expect from it is that I press play and it plays.
Over then last few couple months though. it has become exponentially worse, without any apparent reason (no app update landed in a year) apart from my growing Audible collection.
The problem is, my books simply won't start playing. When I open the app and then a specific book, nothing happens. I click play, nothing happens. I close the book, open another, nothing happens. When I open and close the app a couple of times (think about the stupidity of that), sometimes the book starts to play, sometimes it doesn't. This is a big problem when I need to fumble with the app for fifteen minutes every time I want to play it, sometimes without success. I have tried to reinstall the app multiple times, re-download the books, without success.
Today, I cancelled my platinum Audible subscription, it just frustrates me so much, I can't take it.
I think there are two paths for the WP app going forwards:
- This is the last version of Audible we'll see for Windows Phone. Amazon doesn't want to support the WP ecosystem, but needs to have an app, because Audible is de facto a monopoly and they need it as a defense when EU comes knocking.
- There has been rumors of a slew of new WP apps (Twitter, among others) when WP8.1 hits a certain penetration of the total WP volume and that seems to be right around the corner. Maybe new Kindle+Audible apps are a part of it.
Btw. surprisingly, the Android app on Google Play is not so great either. It works reliably, but the UI really basic and has very little polish.