1) It's hard to care about the character's world because it is so small. I know that there is a town that the characters all live in, but there's maybe ten significant locations that just get used and reused by repeated visitations of the old, middle-aged, and young characters traveling through time.
2) The story is just a string of vignettes that are slammed together for essentially three seasons of television. Each vignette has two people talking in serious hushed tones, there is usually one if not both characters experiencing such strong emotions that they are on the verge of tears, and then there are lots of hugs. And it is this thing over and over and over again. As soon as one vignette ends, you zoom to another location and another time where two characters come together, discuss either how futile and frustrating the time loop is and how no one seems to understand anything about what's going on enough to find a clear direction, and there is always this momentary shock or realization heightened by dramatic music. Oh and the tears. There are always tears.
3) The plot is purposefully confusing and convoluted, so much so, that it actually feels like the showrunners are drawing the story out longer to make it more convoluted and impossible to figure anything out. By season three, you've got two separate worlds each with their own past, present, and future versions of the characters facing an apocalypse which you aren't quite sure would be necessarily bad if you could just get to an end or some kind of conclusion to a story arc. As I said earlier, the world is impossibly small because it is essentially ten significant locations repeated ad nauseum season after season.
4) The characters don't really eat. I've seen eating maybe once in three seasons. But they do smoke, have sex, talk in hushed desperate whispers, and feel the full gravity of their fates while trying to unravel the endless loop of the apocalyptic circumstance that has got them all trapped. There's some teen angst, suspicion, manipulation, but very little eating. It all seems very German, as many of their characters are quite easy on the eyes (so it does have that going for it).
5) Dark has no humor. There is no laughter and there are no jokes. It is one episode after another of intense stares, dramatic tear-filled eyes, pleas of conscience, serious discussions, and hugs.
Anyway, all that aside, I'm actually enjoying the show, because it is science fiction, and I am curious as to how it will all end. Are any of you watching it out there?