Excellent introduction to items not normally explored in the Warhammer 40,000 universe, including the Ecclesiarchy, Rogue Traders, and an in-depth look into the wierdness involved with the transmission of data via sanctioned psykers from planet to planet. Where the story doesn't hold up sometimes in terms of detective stories (though it ultimately comes across as a hard-boiled-detective-in-the-Warhammer-40,000-universe style story), it makes up in action.
This is a great way to look into the daily lives of normal people living in the Warhammer 40,000 universe, as seen through the lens of the Adeptus Arbites. Just as with the Inquisition-focused storylines, you get to see something other than the ubermenschen Space Marines (not that they aren't fantastic as well), and return back to the chaos and mayhem caused by simple human greed.
A good read. Strange, considering I'd never heard of Matt Farrer and he'd produced a trilogy!