WHAT I LIKED:
They found a use for most of the characters, and they're already building to the conclusion.
They brought us back to the Wheeler family where it all began -- characters who slowly disappeared in the prior seasons.
The pacing is pretty good, and I'm not finding myself bored or wanting to turn it off.
WHAT I DISLIKED:
The Robin lesbian relationship is dumb and extraneous. Harry and I feel the same about this one. Very awkward when they try to present it. And when Robin and her girlfriend kissed in a storage closet, they made sure to pan away and barely show the audience anything, so the male perverts don't even get the thrill of watching lesbians make out. Whole subplot is idiotic.
Why so much focus this season on Holly Wheeler, the little-before-seen younger sister of Mike? She was featured so little in the first 4 seasons that I forgot Mike even had a younger sister. Now all of a sudden she's the new Will Byers, getting dragged into the Upside Down by a demogorgon. Didn't we already do this 4 seasons ago? If they're gonna repeat this theme, why not a character we already know well?
The high school bullies targeting Dustin never worked well. They're all way too old looking, and their reason for their obsessive bullying (the belief that last season's "Hellfire Club" brought on the disasters in Hawkins) never really made sense. It's like the Duffer Brothers wanted their own Revenge of the Nerds plot, and forced this in there. I thought we were done with this last season when Head Bully was killed, but apparently not.
The radio station, while semi-realistically done, is out of place and weird. Why was that written into the plot?