I've been listening to readers in school for the past 3 years, and I have loved it. For the past two years I've been working with the same class, and I said goodbye to them today as I've now got a full-time job.
I've seen them make so much progress in the past two years, and have really enjoyed discussing books and authors with them. (They are now all 8-9 yr-olds.) It's also great as a parent to be able to get a glimpse of school from the inside.
The kids were gorgeous today; they all said they'd miss me, and I'd like to think I've made a small contribution to their becoming avid readers in the future.
So if you're thinking about it, don't think, do it! It's very rewarding, and who knows in a few years' time you may no longer have the opportunity.