The actual conclusions of many of the characters like Danny going mad or Jon killing her etc were not even bad and may still happen in the book , its the WAY they got there was atrociously bad and rushed. I sometimes think GRR Martin is taking so long because he thinks "Fuck i was gonna do the same" and is trying to fit different endings that fit with previous books.
this is not even the worst thing of the last 4 seasons
The problem is that they destroyed almost all characters just to simplify their job:
1. Stannis kill his daughter
Reason: to make the audience start to hate him to justify he losing to the Bolton. Then they can use "holy savior" Jon Snow defeat the most evil character of the series. BUT THIS IS THE STANNIS ROLE
2. Tyrion -> he just became idiot and stupid lol
3. Jaime -> they simply destroyed him with just one line
4. Varys and Littlefinger -> the two main players of the game of thrones, which their dispute should be the end power dispute of this story, didnt even face each other again. Littlefinger in the end of the day didnt even show a plan to became king of Westeros.
5. Three Eyed Crow: he and nothing are the same thing
And the worst thing of all: the winter simply didnt happen. Doesnt even snow in Kings Landing
Cersei final villain was shit as hell.