I do enjoy them, but I actually prefer to listen and read along at the same time. I know, it seems a bit pointless, but it gets you really focused on the book. If I'm just reading with a party going on in my brain, I tend to drift off for pages at a time, then realise I hadn't taken any of it in. If that happens when I'm just listening, I completely loose track. With both, I find it really relaxing, as it forces me to clear my mind.
I first got into listening to audio books when the BBC did a radio presentation of Harry Potter and the Philosopher's Stone read by Stephen Fry one Boxing Day. I absolutely loved it. After that, I listened to His Dark Materials on tape. It wasn't just a reading though, it was more like a radio play, with different people voicing different characters. I was kind of freaked that the person who voiced Roger sounded ridiculously like Noddy though...
And I like Stephen Fry's narration. He obviously enjoys it, and he doesn't rush through. I'd prefer 20 disks of him over 5 of anyone else. Well, unless Jo narrated the HP books herself. That would be awesome. She is great during readings.
I kind of drifted didn't I. Audiobooks, regular books, Boxing Day, Noddy, Stephen Fry and Jo Rowling. Now do you see why I need the book and the tape?