Great season. I thought the 80s references throughout were terrific, from Fast Times to Back to the Future to the Neverending Story scene, which was inspired and hilarious. Steve and Dustin were my favorite pair all season, and my favorite story arc was the two of them with Robin and Erica in the secret Russian facility. Steve and Robin were way more fun than Nancy and Jonathan, who are frankly kind of a bore, and I'm glad they focused more on Steve this season than Jonathan. Eleven was very touching and you felt for her at the end. Conspiracy Guy and "Smirnoff" were funny with Joyce and Hopper, and I cracked up at his "Bald Eagle" code name.
Several things about the season are hard to explain away, like how the Russians managed to build a top secret underground facility on American soil that would have taken an incredible amount of manpower and equipment, and the construction of which would have been highly visible. And the creature dying at the end because Joyce closed the portal didn't make sense to me, since it appeared to have survived and grown after the original portal was closed by Eleven. But whatever, the season was a blast. The obvious cliffhanger at the end suggests that Hopper is indeed alive in a Russian prison cell. Of course, how they managed to get him out of that mall when it was surrounded by the American military is a total mystery and will never be adequately explained.