I've had the same experience, Eastwickian. I wasn't immediately taken wtih the CD, but after several listenings, I heard all sorts of nuances that I'd missed the first few times. Now it's a new favorite. You're right about the spoiler effect, though. Still, the secret of the show is not the secret of the novel, as I recall. I found all the performances quite engaging, though I thought Angela Christian's Ann is a bit strident. But then, as she's playing Ann Cathrick, it might be intentional.
"And the postman sighed as he scratched his head, you really rather thought she ought to be dead..."