"Thorn Birds" was a horrible bodice-ripper soap opera of a book. Contrived narrative devices abounded, the characters were two-dimensional cutouts, and the plot was epic only in the number of pages it took to play out. I especially like the end chapters where the author disposes of her characters through a series of ridiculous accidental deaths because she herself has grown weary of them.
I put it in the same league as the "Rich Man, Poor Man" series that befouled the literary space about the same time. But then again, that was the heyday of prime-time soap operas: "Dallas", "Falcon Crest", "Dynasty" ... Bleccchhhhh.