I think the one thing I would change on Audible is functionality a bit more like BeyondPod...where you can put it in landscape to have a "car friendly" button layout (large buttons for ff, pause and rewind), and allow me to "bypass" the puzzle piece lock thing. I would like to see an option of whether I turn on or off the ability to bypass the lock puzzle piece. When BeyondPod is playing I can press the back button or power button and it takes me directly back into BeyondPod rather than making slide the puzzle piece and THEN taking me to the app.
But not a huge big deal...just a tiny bit distracting in the car which is the primary place I use Audible.
They did a great job on the Android version.