I have to say that some of the plot lines are somewhat fantastical but I enjoyed them for all that. The acting was good and once more I am just so impressed at the proficiency of so many European actors in English. And a special mention, as so many others have done, for the young woman who played Venla so incredibly well.
The second season is freshest in my mind as I just saw it last week and I was left with an impression that the series was grappling with ethical and moral dilemmas as well as being a cop drama. The writers took the position that any form of vigilantism is completely wrong even if it were a considered, researched one. And extrapolating from the events in season two, that the death penalty is wrong if only for the fact that the executed person might be innocent.
Tension built as new revelations about the characters grew and explained their motivations. We also saw the very real difference between Finland, the supposedly least corrupt country in the world, and Russia where the authorities collude in lawlessness and corruption.
We also had human interest themes - the aforementioned Venla, infidelity and betrayal, the grisly fate of gays in Russia, relationships with parents.
I hope I'm not making this sound terribly worthy and boring as it isn't. Both seasons were fast paced and gripping. I hope there will be a third.