One major flaw, how the Mist works..
So SPOILERS ahead for the show and the Frank Darabont movie
One thing that bugged me how the mist worked and what was killing people.
In the movie its just mist coming through an dimensional gate and als coming through are all types of lovecraftian monsters. They live in the mist because it´s their natural habitat. Nothing supernatural about the mist.
In the show on the other side, the mist ist a supernatural being itself, reading peoples fears and confronting them with them. This topic is just so overdone and boring, the moment they revealed it in the show i lost interest.
Also the main girl was not cute enough to care for her.