I'm a sucker for Abnett's writing. 40K, fantasy, I've read it all (probably). However, in the same genre, C.S. Goto is some of the most pointless writing I've ever forced myself to finish.
Battlefield Earth, in addition to being one of the worst movies ever made, is one of the worst books ever published in my opinion. I know there are people that consider it fantastic, and probably not all of them follow Tom Cruise, but man...I couldn't even finish it.