Cersei's arc? She was handled almost like a sympathetic victim in a Romeo and Juliet ending with her incestuous brother Jamie, who's redemption arc of his own was ditched.
And after all this time, all these years, after all this preparation, Arya Stark finally reaches the Red Keep only to stop her quest for vengeance after a 20 second conversation and an assumption Cersei will die?
And she apparently has 9 lives like a cat.
It all was mishandled so poorly.