Dart is Barb reincarnated, and will eventually metamorph into her human form. So she'll be "resurrected". The big smoke monster will posess Will, and it will turn out that the Upside Down isn't sinister, so much as just bleeding into our reality. Whatever entity possesses will, will be trying to convince them to help stop the scientist guys.

I'm still holding onto my theory that the entire Upside Down is the subconscious projection of 11's psyche via her powers, making the Upside Down entities creations of her own mind.

I liked the whole Aliens approach, where we get an epic number of Demagordogs (not so keen on the name but I think that's what they called them). That built to a really great finale. Loved the Sean Austin Character, Bob. Liked Max. Her brother worked for me as a secondary threat, but I was hoping for a more supernatural explanation for him and Max's situation than the American Beauty one we got. I didn't quite get the punk excursion. There were some cool things there and a lot of it reminded me of Return of the Living Dead, but it felt weird having Eleven go to the big city while everything else was happening in Hawkins. I feel like they should have either fully committed to a city backdrop or just brought those characters to the small town. It created a weird tone shift. I also wasn't hugely impressed with the Kali character. It was just too on the nose (actress was fine, just the way it was written felt a little heavy handed). I do think introducing her, and reminding viewers that 11 is the 11th in an ongoing project, expanded the world a bit which I could see working well in future seasons. This season definitely didn't surprise me like the first, but that is a pretty high bar, since I just wasn't expecting Stranger Things at all the first time around. Glad they kept Barb out of it. Don't think I needed them to deal with the parents grief or have Nancy deal with it in the way she did. Nancy and Michael's father and mother had less of a presence in this one, but they both had some great moments. Liked the Paul Reiser character as well.

There were points in this one where things dragged. But once it got going, I had trouble  not binging the rest of the episodes (I watched 7 episodes in a row yesterday). Given that was my reaction, I'd say it was a good season. I'm kind of curious where they will go from here.