The readings range from adequate (Does a life at sea really reduce one's voice to a Tom Waits growl? Ahab impersonators seem to think so.) to entertaining to incantatory.
Readers include M-D-related authors (Nathaniel Philbrick, Andrew Delbanco), Masterpiece-Theatre-caliber actors (Tilda Swinton, Stephen Fry, Benedict Cumberbatch), and the odd UK Prime Minister.
Apparently, many of the readers are well-known in the UK. This blog by M-D virgin and reader-with-lovely-accent, Eva Stalker, gives the credentials of most of them.