The first season was 10/10. I can't quite articulate what's been lost in seasons 2 and 3. The mystery I think? Part of the horror was watching people struggle against an unknown enemy - a single unknown enemy, another of season 2's downfalls. Also the fact that the children, teens, and adults were initially separate, fighting the same problem but with slightly different stakes and information, was really fun to watch in the first season. None of this is to say later seasons were bad (though 3 was better than 2), but they don't live up to the brilliance of the first season