A couple of months ago, I signed up for Audible. My first order was Gibbon's The Decline and Fall of the Roman Empire. It's 126 hours long. I'd be lying if I said I finished it.
The audio is high quality and Charlton Griffin's narration is excellent. It's hard to believe this book is 200 years old. If you merely want to read this book, it is also available on Gutenberg. This version is also excellent.
One thing that you miss from the Audible version is the maps. Gibbon meanders through history and of course he assumed you'd be holding the book with the maps as you read. I am surprised that Audible provided a PDF for the record, but didn't include the non-copyrighted maps. It is an odd omission. I have pulled the maps from the Gutenberg copy and loaded them here. Perhaps some day I will make a PDF of just the maps for easy printing.
The list price attached to the ad is for an purchase outside of your Audible account credit. An Audible account is $14.95 a month, which entitles you to one credit or book per month. Well worth the cost.