I'm currently reading the first book in the Warhammer 40,000 book series The Horus Heresy; titled Horus Rising.
It's pretty good. Since this is apparently technically 10,000 years before Warhammer 40,000, it's not very grimdark and shows quite a lot of humanity in the characters. They even mention near the beginning how treating the Emperor like a God is laughable.
However this humanity leaves some amusingly affectionate moments between Space Marines, that one could quite easily jokingly call homoerotic.
Check this out:
"As the sparks of it [vapour flare] rained slowly down onto the waters, the four warriors hugged and whooped, clasping hands and slapping backs. Torgaddon, Aximand and Abaddon took turns to embrace Loken."
If the other books are as interesting I could be reading for a while, but I'm a bit worried about how consistent the writing style will be since the series has many writers, even though I am aware they work together for them.
[small]The only thing I can consider a slight downside so far is they quite rightly feel the need to give you a character glossary for the book that's suprisingly long so you don't worry about forgetting who's who. Despite Horus being the person who's going to be a huge dick at some point, he has my favourite name. Since it's not made up, it has only one word, and is only five letters.[/small]