[dworth]

I would suggest reading the other Warhammer 40K novels before the Horus Heresy ones. The Horus Heresy is a historical event in the WH40K universe, ten thousand years prior to the 'present' which pretty much defined the current Imperium and represents its fall at the peak of its power. Whilst it's been part of the WH40K canon for over twenty years, the Heresy wasn't described in much detail until these books came out. There's a lot in the books that alludes to WH40K history and to things in the 'present day' or describes in detail things that had only been the stuff of myth, rumour, the Imperial Cult and conjecture before.

In other words... it's like watching Star Wars Episodes I, II and III before the original trilogy, if that makes any sense. You can enjoy them, but you won't get the most out of them unless you have knowledge of later events. I've been into WH40K for over twenty years since the first edition, so I love them (with a few exceptions).