Worst book even
I don't know for sure, but if you ask me to name the "Worst Fantasy Novel That I've Read All The Way Through" there's only one contender:
Blue Moon Rising aka Darkwood
by Simon Green aka Simon R Green
(I think the R was added to the name along the line somewhere, perhaps he's working up to adding another R to sound even more classy? I've included this info to make it easier for everybody to avoid.)
I bought this on a recommendation from Interzone Magazine, shortly after it was published, in 1980 so you can tell what a fossil I am. After reading it I cancelled my subscription.
The author can't plot, he can't do characters or dialogue, his fantasy world is thinner than cellophane and as full of holes as St Sebastian.
He's also lazy. He can't even be bothered to make up fantasy names for his places and people - yes, eye-splitting celtic jumbles of letters are not de rigeur for fantasy, but he could have been more original than "the Forest Kingdom", surely.
But, oh dear, he can tell a story; or at least he has the knack of making you wonder what is going to happen next. He has that in spades. He even appears to use the advanced technique of making you believe that this must all make sense in the end because otherwise it would never have been published.
So I dragged my sorry brain to the last sentence of the last page before throwing it across the room in incredulity and disgust. Then in a fit of altruism I wrapped it in brown paper and put it in the bin. I wasn't going to give it house-space, but I couldn't in all humanity send it to charity, and I'd have felt dishonest selling it. It was better that no-one else was harmed.
At least it taught me that the ability to write a compelling story was not the be-all and end-all, (even in fantasy, where publishers seem to think that the buyers have a low literary threshold). For me, story telling is absolutely neccessary, but it really isn't anywhere near sufficient. From then on I learned to spot the signs. "Bin before you get sucked in".