It was good, but slow. I figured the entire episode would be about the battle, but it still seemed to advance slower than I had anticipated. It was also far too dark, that even though I watched it at night in a dark bedroom, I missed many scenes due to ghosting.
Having put those negativities out of the way, man, this was a good episode! The fire going out on the dothraki tribes, the sense of imminent doom, the massive army of the dead. The absolutely beautiful scene of the dragons in front of the moon (was this the first time we saw the moon in this show?

). The story of Beric coming to an end, finally having fulfilled his purpose of saving Arya.
I'll be fair, I did not expect the Night King to go down this episode. However it was quite a ballsy take by the directors, not to leave the bad guy until the final episode and have a they lived happily ever after moment, but rather taking him down early on. I still expect there will be more going on between Bran and the Night King that will be covered in future episodes. I also expected more people to die, but I disagree with your statement of no important characters dying. The loss of both Mormonts is the end of an entire house, and a strong one at that. They both went out fighting like true soldiers. Theon finally redeemed himself, running towards danger rather than away from it. Yes, some others should have probably gone down (Sam, Brienne, Jaime), but I'm sure they'll meet their demise eventually. It is Game of Thrones after all.
I honestly have no idea what they will do in future episodes. Yes, the fight with Cersei is still there, but we've got 3 episodes to fill. What have they still got in mind for us? Looking forward to it!