Hah, I just read a one-star review on Goodreads, because the narrator was boring. Goodreads is reviewing the book itself, not an audiobook adaptation.
Also, all I could think of was the Seinfeld episode where George wanted audio books, because he couldn't stand reading in his own voice, but the narrator ended up sounding exactly like him.
Goodreads also has listings for audiobooks. Reviewing the narrator in an audiobook is like reviewing the font choice in a paper book. Both are legitimate. (If someone's posting a review of an audiobook to the listing of the main format, that's wrong)