I watched this episode the night it dropped on New Year's Eve so I've had some time to digest it. I have also had time to hear or read about a ton of complaints about the finale. This may be a little too late to really save anyone as most people who are interested already watched it, but if you haven't, I might be able to increase your joy when you do watch it.
When you watch the finale, please turn off your brain. Please remember that this all started almost 10 years ago as a fun love letter to growing up in the 1980s and to cheesy 80s shows and movies like Tales From The Dark Side and The Goonies (Elle is even wearing the exact outfit Josh Brolin wore in the movie) with some Stand By Me mixed in (plus any other supernatural 80s stuff you can think of). It was not intended to change the world. It was not intended to be some kind of deep thinking mystery we all had to solve. It is a popcorn show about a popcorn generation.
The main complaints I have heard is that the show didn't live up to peoples' expectations. I would argue that is on the people who expected Stranger Things to be more than it is. It's just fun. It was really cool fun but fun nonetheless. It seems the people most angry are the people who read, watched or created all sorts of complicated connections to scenes from the five seasons. Some people thought all sorts of Easter eggs from the previous seasons would all be found, collected and displayed in some kind of earth shattering reveal. They went over every detail of the previous 41 episodes and thought it would lead to a very specific conclusion they had in their head. But that is not what Stranger Things is. It's actually a pretty simple story of good versus evil. It's a Dungeons and Dragons Campaign run by a kid. It isn't Brennan Lee Mulligan running this thing. Not every little detail will be remembered and brought back to mean something later. Sometimes fighting and killing the big baddy is the entire story.
I am not saying that people who looked too much into the story did something wrong. Heck I do it all the time. And I know from personal experience that when you spend so much time and energy trying to predict what should happen it can totally ruin your entire experience when what should happen, simply doesn't. I didn't write the story but I thought I could out think the writer. The best example of this for me was The Force Awakens and The Last Jedi (which was objectively a train wreck no matter how much you did or didn't think about it). But what ruined the sequels for me was the fact that I spent so much time and energy looking for clues as to who Rey's parents were. I was convinced she was Luke and Leia's child. I was convinced she _should _be their child. I mean the look Han gives her on the Millennium Falcon when she says she's never seen so much green combined with Leia bypassing her old dear friend Chewbacca to hug a complete stranger should have led to Rey being their daughter. But she wasn't and damn it did that piss me off (still does).
But that was my fault for dropping into the "should trap". If I would have just sat back and let myself be entertained, I may have enjoyed it more (well probably not because The Last Jedi was a disaster).
So my advice... DO NOT FALL INTO THE "SHOULD TRAP" with the Stranger Things finale. Just enjoy what it is. And what is it exactly? It is a pretty simple ending where the big baddy and our heroes square off for one final battle. It completes all of our favorite characters' stories. It wraps up loose ends and doesn't do anything too risky to ruin the show forever. And I give them my highest praise for not doing something shocking just for the sake of being shocking. You are a fun show. Just be a fun show with a fun ending. Done. Don't get too full of yourself. Don't think you will make cinematic history. Just be fun! ("Make me a me a bicycle clown!")
It might sound like I am being overly generous by giving praise for simply not messing up the finale... but I have seen shows ruined way too many times to take it for granted that the creators will not do something show-destroying. If you need evidence, just look at the endings of Sopranos, The Wire and How I Met Your Mother. I probably won't watch those shows ever again because their creators screwed up the endings so badly. And those weren't ruined by the "should trap". Those were ruined by creators either trying to be clever or just forgetting everything they have ever said about a character.
So Stranger Things' ending didn't ruin the show. I will definitely watch every episode again some day (probably when I am retired). When I do, I will be sure to turn off my brain and just have fun! And I am sure I will enjoy them just as much or more than I did the first time I watched.