What fascinated me and kept me awake though, was not really the story as much as it was the changes in the voice actor's characterizations. Her characters began changing from how she first interpreted them. One female character in particular developed from a very haughty, highbrow, "full of self-importance" sort of woman, to pick up a completely different, coarse accent from a lower strata of English society. I don't pretend to be an expert on British accents, but I have watched enough BBC mini series to acquire an opinion.
In all fairness, this voice actor was phenomenal in her ability to create so many different characters and keep them straight for such a sustained project. Her characterizations worked well through the majority of the book. They didn't show big changes until towards the last few chapters. I kept wondering if she had some inspiration that made her change the tone and inflection and accent of her characters? Or was she just plain tired of the project? Didn't her sound engineer give her feedback? Or did the dialogue suddenly resemble a character from a different book that she just fell into the traits of that character by accident --- unknowingly?
Personally, I think the character's dialogue just started sounding like another character from a different book. (It sounded familiar that way to me!) Sometimes authors run out of inspiration and "borrow" snippets from here or there, even from their own previous work. So, the fault of the change in interpretation was probably not all on the shoulders of the Voice Actor. She may not even be aware that she had strayed so much.
For those of you who read stories to the grandkids and try to act out the different characters using different "voices," good for you. I promise that I won't come to your house to listen and criticize.