Worst movie adaptation of a book EVER.
I don't think there could be a fair adaptation (I have not read it).
Wouldn't the continuity need to be sliced up and randomly pasted together?
I'd say the 60 minute Monogram B-movie adapted from Harry Stephen Keller's 400-paged "12 Coins of Confucius" probably missed much (they made for that by casting Bela Lugosi as the villain).
Of course, the hour long version of A Clockwork Orange by Andy Warhol (called Vinyl) was probably very lacking. I've read alternate descriptions claiming that it was authorized and that it was unauthorized. I'd have to look it up again to confirm is this was a legitimate adaptation.
And David Lynch's Dune was probably somewhat off. Don't know how Alexandro "El Topo" Jodorowsky's Dune (with Dali, Groucho Marx, and set design by H.R. "Alien" Gieger) would've been.