As i said before, Arya was most likely the only character that had a chance at killing the night king. No one else could have defeated him in a 1vs1 or even a more-than-1vs1...then for me the issue is, the entire Serie started with them, they were considered the biggest threat ever seen in westeros, than boom, 5 seconds, night King stabbed, and everything is done. We have so little information about them. How does the night King creates the others? What did he do all this time before the winter? What was the connection with Bran? It looked almost like they didn't even try.
Same with Cersei, and to some extend Jaime (I still cant belive Euron was able to hit Jaime TWICE, or that he was even able to Kill a dragon). She didn't even had a last showdown with Daenerys or Tiryon (or Sansa, would have liked a reunion for them). It was like they went for the easy way to kill them, forgetting or even defeating all the characters grown till that point.
Then, I belive the Daenerys change of mind was somewhat easy to call.
The issue in my opinion is with Tiryon and Jon, starting with Varys death. They both let her execute the only real "good" character of the Serie (like, ha was actually really good, thinking about the people) without saying anything.
I personally am not liking Jon this season at all, and I think Tiryon lost all his wits.
Now let's take a second to remember how Davos was in every big battle in the Serie, and survived them all.