Overall very good episode but a lot things bothered me. First it was shot so dark it was distracting trying to see what was happening and I found myself missing specific action.
Second while the scene was brilliant i hated how KN was killed so soon with so little story/info. In addition I wasn't rooting for Brienne or Jaime to die but it annoyed me to see them in an impossible situation several times and appear to have survived mainly unscathed. Sam was laying on the ground most of the episode and at the very least should have been trampled if not outright attacked by the dead but it didnt show him die so I assume he survived. Bran, the dragons and in a way Jon were almost useless. Why didn't Melisandre light up everyones weapon?
I loved the scene with Lady Mormont and the giant. She was a bad ass. Same with Arya, she was fantastic.
Im with you, the battle scenes were very well done, but I have a few critiques:
1) After all this time, and all these gyrations, it felt like the heroes got dropped into a sequel to 28 Days Later. I mean I know they are the dead, etc. but it just so much like any zombie movie to me.
2) As I(unfortunately) assumed, no one who was really important died. Like OP said, how many times can you put the same characters in impossible situations and then save them? This show simply doesnt have the balls it did when it started. Remember when they killed Ned Stark, basically the main character, just like that? Now even 2nd tier characters like Brienne and Samwell are allowed to live? Meh.
3) The dragon battle how SO much potential, but it felt a little hard to follow. I guess Jons dragon died? I couldn't tell for sure even though he crash landed. Also, why did Dany land her dragon in the middle of the dead so it could get mobbed? Made no sense to me at all. Also on the dragon front, what was the point of Jon playing peekabo with the dead dragon in that last scene? Seemed like a complete waste of time.
4) I felt like they made it way too obvious that Arya would kill the NK once she had the conversation with Melissandre. I wish there was more of an epic fight between the NK and Arya, kind of felt cheated that someone so powerful(couldnt even be killed by dragon fire) was dealt with so easily. Missed a chance for an epic duel. I was actually thinking(and hoping) that she went there to kill Bran(who I was also hoping was warging into the NK) all this time. Might have been hard to pull off given previous happenings, but would have been a much better story IMO. Bran seeking revenge on the Lannisters, then getting drunk with the power of leading the WW army. Oh well.
5) Finally, really annoyed that Cersei just got to sit out the entire battle for some reason, and not pay the price for it. Just dont see how the North will hold her off this season.
What I liked:
1) Arya is obvious, but I just thought it was worth pointing out that her fight scenes are tremendous. She makes you believe a 5 foot nothing, 100lb girl could kill all of these things. She deserved to be the one who ended the NK.
2) Building the moat surrounded by the ring of fire was pretty cool, although I am surprised the defenses of the wall itself werent better prepared(boiling oil, large stones) to keep the WW from climbing. The look of Winterfell was awesome.
3) Lady Mormont got the death she earned on the show. She is literally the only character that I cared about who died. A tough little warrior right until the end, and took a bad boy with her!
4) Jon showing the balls to try and chase down the KN knowing it would mean almost certain death. I actually wished they would have killed him off there, so Aryas eventual act would be that much more powerful. Another missed chance for that epic NK duel lost.