Finished it late last night.  Thoughts included.  Slight spoilers.

• Bob (Sean Astin) is really an interesting character.  I think he’s the dad most geeks would have wanted.  There’s a particular scene that is 80s horror trope, and you see it a mile away, and it really drives home the theme of this season.
• Joyce and Hopper seems forced.  Joyce finally moves away from hysterical to driven, and goes deep into mom-mode.
• Hopper spends an entire episode making horrible decisions.  Narratively required, but not justified.  There were other methods to reach the same end point, this was a poor writing decision.
• Jonathan, Nancy, and Steve triangle doesn’t work as well as it should.  Jonathan and Nancy clearly have better chemistry.  It’s forced and corny, but you can see it underneath.
• Nancy provides too much exposition and little character growth.  Until the last 5 minutes of the series.  Seems a tad wasted.
• Jonathan does a serviceable job and surrogate dad, big brother.  He moves further away from self-doubt.
• Steve.  My man.  If they made a series just about Steve, I’d watch it.  He is the star of every scene, and continues to bring a level of realism/grounding to the surreal events.  His character arc is just amazing, coming to terms with the mortality of his fame, his role in the big picture, his openness with Dustin.
• Dustin has highs and lows.  There’s some good growth here, and he’s that trash talking kid everyone got along with.  His buddy comedy with Steve is the backbone of the tail of the season.
• Luke is great.  The rage he felt in the former is replaced with trying to protect people in the second.  His relationship with Max is believable, full of the same hurdles all teens go through.
• Max is interesting but takes a bit too long to develop, then just seems to stall.  Everyone seems to have a role, but hers goes away too quickly.
• Billy is something else.  Our version of the upside down monster.  There’s just enough there to realize that he has his own demons, and that he’s riding a knife’s edge to keep sane.  Borderline psychopath.  Some solid potential.
• Mike.  He’s there at the start and there at the end.  More of a lost puppy than anything of real value.  He’s the heart of it all, certainly, but that’s about it.  His dislike for Max seems forced… he’s a team leader but rarely acts like it.
• Will.  I won’t spoil it but he needs a character arc that makes sense for the next season.  He’s only there for exposition and story purposes.  Well, minus the first 3 episodes, where there’s potential.
• The supporting cast is top notch.  Paul Reiser goes against type and delivers.  Kali (8) hits the right note for someone who had to grow up alone and is full of anger.  Her posse isn’t too bright, minus Funshine (Kai Greene).
• Eleven has 2 solid episodes of growth.  The 2nd one feels forced, and teaches her the difference between killing and being a killer.  Her relationship with Hopper works, from her perspective at least.  She’s a bit too much the “golden gun” for the overall arc, as most of the other characters provide minimal value (‘cept Steve, that boss!)

The overall horror arc has bits that work, others that don’t.  The start is more John Hughes, and the middle gets into Steven King land.  Overall, I’m certainly satisfied but it does less than the first season.  The main issue is that we know 6 of the main characters in many situations (Mike, Dustin, Luke, Eleven, Nancy and Steve), and how they act here isn’t exactly new… and when they don’t stay in character it’s jarring.

It is still binge-worthy. It still makes you want to see what comes next.  It’s still one of the better series that we have available.  And any series that has a Mindflayer as a main villain, I’m in.