At long last a serie which doesn't depict life in a police station as a happy endless chase against the bad guys.
Here, life is a bit desperate; people in the police team depicted in this serie clearly have a social problem (they sometimes look like as social as a gang of grizzly bears; the Rivière/Frane relationship is emblematic I think); but is this social problem theirs only, or the problem of the society as a whole?
One of the great qualities of this serie is that it doesn't attempt to hide between political correctness (usual US cop serie defect) or overenthusiastic positivism (usual French cop serie defect); in Police District, it's clear that the street is filthy, and that a member of the police has to chase the villains in the dirt of villains' world.
Another is it has a refreshingly different set of inhibitions as the usual mix of cop series (70% US - 30% FR over here); people drink, people swear (may be great for foreigners willing to learn the colloquial aspects of French...), the procedures are different (Latin rather than Anglo-Saxon judicial system), etc.
In short, I just wish there were more than a handful of episodes per season, and I look forward to season four!