The only real negative I had with the show was the monster. It was intimidating at first but the more they shown it off and we saw how bad the design and quality of the CG was, it lost all impact. They should have also used practical effects, shocked they didn't considering what the show was going for.
But other than that, I thought it was one of the best 80s throwback works ever. It nailed pretty much everything from the soundtrack, storytelling beats and sets. Those kids were also great actors, some of the best I've ever seen. I would love it if they go for more of a sci-fi angle next time as opposed to the supernatural.
It was mostly practical - a guy in a suit.