I would give season 1 almost 10, but its not perfect so its a solid 9.5. I really wish if the ratings for titles are per season rather than all seasons collectively. Each season should deserve its own ratings. Like many have stated, the 9.0 rating for Stranger Things comes from the season 1 ratings not so much for season 2.

We all know season 1 was rock solid... its massively captivating, mystical, thrilling, adventurous and has decent amount of horror. The whole atmosphere, the story line and characters are all very well done. Life in Hawkins and all the general characters adds essence to the whole story. You get hooked in to the show on episode 1 itself.

Season 2,... well, the big things about season 2 is that it answers some of the questions come across in season 1. I also think season 2 sets for future seasons by introducing more/new characters to the story which otherwise seems unnecessary (waste of time) for the season 2 itself... such as Max and Kali (08). But overall, the season 2 does not have the same intense of season 1 or the that captivation - not that its an easy thing to maintain through another season. Biggest fault for me was that most of the season 2 story is somewhat predictable unlike the season 1, and also the story line was not as connected as season 1. Saying all that, I still enjoyed season 2 other than couple of episodes... but overall its definitely not as same as season 1. If I rate season 2 I would give it a 7.5 or so.

Just hopes season 3 will be as good as season 1. Overall, good work by Duffer brothers !!!