UPDATE: 18 March 2015, it seems that the beta improvements HAVE now been rolled into the official client, so if you have that installed, just look out for the update hitting your on-device Store.
From the Store entry for the Audible beta client:
Not enough time for all the books you want to enjoy? Download the app by Audible.com, an Amazon company, to listen to books on the go.
This is a beta release of the app for users who want to help test the latest build and are willing to tolerate the bugs that may come with a beta. Please provide feedback to email@example.com or use the app (Settings & Support > Help -> Feedback and feature request).
This release includes:
- Bug fixes
- Improved stability
- Personalized recommendations
- View similar titles by the same author, narrator and next in series
- Rate and review titles from the app
- Play audio samples in the app
- Storage card support
In the fullness of time, of course, this beta version will be matched by the official, 'stable' version (ironic, considering the number of bugs!), but there really is no penalty for having both on the go at the same time. The interface is extremely similar, with just the lack of bugs and issues to distinguish them.
A few screens of the Audible Beta client in action today:
Recommended if you like audio books - this client is certainly up with the functionality of the iOS and Android clients now. Grab it here in the Store.