This weekend I started and finished Dan Abnett's Warhammer 40K novel; "Brothers of the Snake". I am reading Gaunt Ghosts series nowadays and it was a nice change for me.
The novel turns around Priad; a Space Marine and tell us about his undertakings in a series of short stories like his first mission as a initiate, how he became squad-sergeant, etc. (I do not want to give too much spoiler.)
You can also find rituals of a Chapter and daily life of a Space Marine, how they are seen by mortal people, how time works for both. I would recommend this book for all Warhammer 40K players, especially Space Marine players as they will be deploying their army in quiet a different mood next time.