I'll correct on my previous post. I did like Storm of Iron and much of his Warhammer Fantasy contributions. The former is particularly special because it's one of the first Black Library novels were Chaos actually won.
That was a pretty amazing event, especially to Chaos players like me. My Emperor's Children army was also at least inspired by his work with Fulgrim as well.
Really, everything else is ''meh'' or somewhat good. Except for McNeill's Ultramarines. I particularly loathe his Ultramarines series, McNeill having written the Ultramarines as hidebound morons save for his pet character, Ventris. What's worse is that other authors appeared to have picked up the interpretation. It's gotten so bad I stopped playing Ultramarines because of his novels.