Audio books: you either love them or you've never listened to one in your life.
Personally I've been a massive fan since I was a young 'un with problems sleeping. Instead of tossing and turning and fretting about my inability to sleep I would simply whack The Giraffe, the Pelly and Me into the tape player and let Roald Dhal's prose lull me to sleep.
These days I use them sometimes for exactly the same purpose but also for a range of others: to keep me entertained on those rare occasions I dust off the running shoes for a leisurely stroll and to entertain me when I'm driving about/cooking/loafing about.
There are pros and cons, obviously. For a start, sometimes you get a complete freak reading a book and it doesn't matter how good it is you just can't stick with it. I believe I've recounted on here once before the classic Italian lessons I once downloaded, only to discover they were being read by a man who sounded like he was having a stroke. Good times. It's also somewhat easy to lose the thread of the story if you drift off or let your mind wander. I tend to drift off in bed only to wake up with the ipod in the small of my back, my earphone wrapped about my throat and no idea where the audio book left off and my dreams began.
On the other hand, there are fewer great delights like listening to Mr Dahl himself read that children's story classic Fantastic Mr Fox, ditto for hearing Stephen Fry plummy-tone his way through Harry Potter and fuck me if I wasn't captivated just the other day by Steve Martin reading some of his rather good short stories (yeah, who knew?).
The only real problem is that I have exactly the same bad habits with audio books as I do with regular books. By which I mean my ipod is currently cluttered up with Faulkner and Burroughs and plenty of brainy non-fiction type of books that I do honestly INTEND to read. However I tend to go in for relistening to old classics (while my electronic bookcase sloowly fills up) or (my current fetish) listening to the truly awesome (and often unintentionally hilarious) 1950s BBC adaptions of the Sherlock Holmes books.
Which brings me to my final point: the role of the audio book as An Event. No longer do we sit about the radio, darning socks while listening to a serialised drama. And a bloody good thing, too, because no doubt it would be enough to make one go out and contract bloody consumption just for something to do in the evenings. But although I may be reclining on my couch, rather than sitting in a straight backed chair, and I may be fecking about with cards, rather than doing anything at all with a sock, there is something truly delightful about putting on a Sherlock Holmes serial, dimming the lights a bit and leting oneself be carried away by the shoddy production values of the 1950s. Ahhh.