The Letter Scene *spoilers*
My god, that scene was absolutely heartbreaking to me, leading right into the song "Heroes" by David Bowie.
It absolutely crushed me. The new letter Hopper wrote, instead of what he was going to say, with what he wrote about life being hard, and sad, but happy and surprising sometimes...and El just breaking down sobbing while reading it, mixed with the cutaways to Hopper writing the note with the voiceover. That scene was brilliantly done, and it hit me hard. Was not expecting such an emotional impact watching Stranger Things, haha.
Millie Bobby Brown was phenomenal in that scene as well.
Damn. Well done with the sad ending.