I loved the initial season of Dark, it was flawless all-around. The season 2 was bit weaker, but still quite good. The third one however, was a disaster IMO. By adding another level of complexity to already pretty complex show, it just became difficult to watch to me and not fun. Especially, when all of it was tied to the event from previous season, which aired year before and i did not remember every little detail. I honestly believe the creators went over the top, they have absolute winner on their hands, but did not know what do it with it, it had literally potential to be top 5 show of all times would it be handled better.
Additionally, i felt it veered off from its sort of initial first season promise of being bit of "cosmic horror" thing, it was at times alluded the Hanno/Noah character to be possibly some kind of incarnate of devil, which indeed, did not happen in the end, and i suppose i would have liked it bit more, if the show had that dimension.
You know, bit of a Event Horizon vibe. I think Castle Rock in its first season especially, despite not being as fun to watch as initial season of Dark, would say even boring and dull to watch at times, did better job in that regard.
The ending however, was rather satisfying. It sort of explained everything and concluded things, that was the silver lining.