I've been using Audible for years, I started with 1 book credit and now have the 2 credit a month which works out at £7.50 a audio book. It has a huge range of books that cover every taste. I myself have a love of history and listen to them while I do my housework or walking. I have the books on both my iPod and on the app for my iPad and I love it, I don't always have time to sit down and read so having them read to me while I do other things is great. It's also great for people who enjoy books but whose sight is not as good.
The credit system provides a good deal on audio books, I feel that the 1-credit per month option is definitely worth the £7.99. Returning a book you were unsatisfied with, and picking a replacement, is extremely quick and simple. Knowing I will be able to return a book so easily makes me more willing to take a punt on a book I'm curious, but unsure, about. They could probably put more effort into their marketing of fantasy/sci-fi, as offers also only seem to be available on the really big-name items (those that most who enjoy the genre will already have read).
After cancelling in the free trial period I was charged for at least 2 months membership fee. After advising the customer service team of this they have done nothing to rectify the situation. Very unhappy customer.
On Audible.co.uk you can find a very large amount of audiobooks, all in high quality. You can also hear a little demo of the audiobook before you buy it. When you buy it, you get immediate access to download it, and it's easy to listen to on your computer, or through iTunes and then on your iPod. Even if you delete the files on your computer, you can download them again.