OP: Audio books are excellent; they don't replace reading for yourself, but they provide a whole new world of enjoyment I think.
Having lost all reading vision ten years ago (I have some useful peripheral vision), I have quite a few opinions about audio books!

The thought of not actually reading took a moment or two to come to terms with, but the first thing I did was buy a CCTV which meant I could read ... but slowly of course. This, I quickly realised, was not such a disadvantage as I thought it would be, as I found that in some ways I enjoyed the book more, having taken longer to read and think about the characters and settings. Similarly with audio books, I found I got more out of them really ... I was always a fast reader - I used to
try and read Terry Pratchett's books more slowly, so that I could extend the enjoyment, but found it very difficult!
The voice of the reader is very important. Some read so well that you don't hear the voice, you hear the story (for example Diana Bishop and Richard Dawkins - it's a pity he only reads his books and the new 'Origin of Species'). Some try to act it as a play, which is really infuriating - I'm not reading a play, I'm reading a
book for goodness Sake! Some voices are so mellifluous that you forget the text and hear the voice!
Audio books are one of too few ways to use valuably the time driving a car.
And a great way to give rest to your tired eyes at home, have a book while lying on bed with your eyes closed, instead of straining your already tired eyes in dim lamp light all evening.
The difficulty here of course is that you fall asleep and then have to try to find where you were! This is much easier with cassettes but of course they're being phased out.
Audio books are usually shortened and simplified versions, they are a compromise that doesn´t say exactly what the author intended to say.
Sometimes it's all you can get, and the unabridged ones are much more expensive, but libraries usually get full versions eventually, so I have learnt to be patient and wait! I use a Daisy Reader from the NLB (National Library for the Blind) and they often use volunteer readers, and do not, as far as I know, do abridged versions. They have a wide range of titles.
With an audio book it is more difficult to stop or slow down marveling at the meaning or entertaining excellence of a specific phrase.
Yes, this is a definite disadvantage, especially if it's a book which has several threads running through it and there is no indication at the beginning of a new section which character is being talked about.
There are a few times when I have not been able to continue with a book because of an irritating, set-your-teeth-on-edge reader, but I have also set up a new routine for myself for the last two and a half years. I have two readers every week (and a young student who comes during her university holidays). This means only a short part of the book each week, but it has proved to be a really excellent way of having access to all sorts of books. They each come for an hour each week.
I've tried listening to some things with synthetic voices, but have not yet found a way of enjoying this way of listening.