Everything with Dustin is an absolute highlight this season. Going from one of the sweetest dorkiest characters, into them effectively being "Punished Dustin" flows surprisingly seamlessly with how the character has been thru the whole show, especially with how his relationship with Eddie impacted him. I really love that his rocky relationship with Steve from Season 4 carries into this season and isn't just layered over or forgotten. They both clearly care a lot about each other, but are very stubborn and have grown to become very different people than the versions of themselves that met years ago. I'm very satisfied with where their arc together ends up by the end of this batch.
I'm also really satisfied with Lucas' arc so far. Saw someone point this out recently, but Lucas has always styled himself after Steve, since he was the one to save them in Season 2. This leads to him trying to be a cool kid and school athlete in S4, styling his hair and working out; only to find exactly what Steve found out in S1: that the jocks and cool kids are awful friends and awful people, reaffirming his loyalty with the dorks.
Unlike Steve though, he is never actually successful in saving the people he cares for. He very nearly loses Max multiple times. He wasn't able to save the kids from the Demogorgons in the tunnels in S5A, the way Steve did for him. Both Eddie and multiple of his jock friends die against Vecna. But despite every loss, he keeps consistent and he doesn't waver in his dedication to his loved ones. And in the end, the wrap-up of the incredible "Running up that Hill" sequence, the best scene in the show, is Max realizing that it wasn't really Kate Bush that made her resist death and fight to
live again and again, it was her loved ones. And specifically, Lucas' consistent love and attentiveness through everything. I think that's a great way to put a bow on both characters' narratives.
Lots of messiness this season. Lots of moments of genuinely poor writing and unfinished visual effects. But also just enough genuinely great moments and character-driven scenes to keep me going, and for me to be satisfied enough with Stranger Things as a finished show.