My complaint about this show [spoilers]

Dark is very good overall. It's extremely complex and has an internal consistency that most shows can only dream of.

However, the rampant plotting leaves very little space for characterisation and spirit. There's plenty of tragedy and sorrow, but not a single note of humour to leaven it. The characters are largely indistinguishable apart from their names and appearances (which aren't a given anyway). They are generally dour, pragmatic and occasionally enigmatic (when the plot demands it). One personality type prevails. Only Jonas seems to have a real passion for anyone (Marta). The rest are just moody, bordering on frenzied, about their missing or cheating relatives.

The missing human element prevents this show from becoming truly great, in my opinion. I like a puzzle as much as the next person, but a puzzle isn't art.