I've been an Audible fan for far longer then I've owned an iPhone; when I first launched the App Store, Audible was one of the first things I searched for.
Thanks to some of the changes made in iOS 4.0, some of the largest challenges for an Audible iPhone app we've written about in the past are no longer a problem. I'm really excited that a free Audible app has finally arrived on the App Store!
Ironically, while you can create an Audible account from the app, you aren't able to browse Audible's selection or purchase books; plan on making a round trip to Safari whenever you want to buy something. Additionally, there are some older titles that have not yet been made available in a format ready for wireless delivery, but Audible claims over 75,000 titles are available.
One annoyance with the application is that you will need to be connected to Wi-Fi to download any files larger then 20MB. While this limit isn't particularly surprising given similar restrictions in other apps and the App Store itself, it is a limit not shared with at least one other Audible app on a competing platform.