The stop motions scenes near the end

I agree that doesn't make much sense to me either how a movie could supposedly be your favorite horror film of all time and then all of a sudden you don't like it anymore? That usually doesn't happen with a movie you have ever considered to be one of your all time favorites unless you just never really cared too much for the film to begin with. But besides that, I think the animation in this movie still looks pretty damn cool and very different and it just looks really creepy. I would so much rather see stuff like this than any kind of crappy CGI which to me hardly ever looks good no matter how cheap or expensive it was to create.

Make perfect sense. You are much younger probably never watch that many horror movies, this one was different from most of the teen slasher movies of the time which were very much formula movies of large group of teen get picked off one by one by going off to fuck each other only to be fucked by the baddie of the movie. As for effects or lack their of, again you've got a younger viewer that isn't as sophisticated and the first time they are watching it they gloss over the bad things focused only on what they enjoy.

Pretty much like the first Star Wars, when it came out I thought it was the greatest movie ever.. decades later I tried to watch it with my kids and it was a complete let down. I couldn't watch it anymore... the bad acting, Styrofoam production sets... it really wasn't watchable to me anymore. So I can see that happening with lots of older movies that people saw when they were younger. It is a bit like your first fuck... you never forget it, but if you think about it in a detached way it wasn't the best fuck ever it just seemed that way at the time.

There is a bit of stop motion - check when the tentacles burst up and grab the detonator/plunger.

I had no issue with the stop motion stuff. To me it made the movie weirder & much creepier in some scenes. I liked the dark lighting & sick sense of humor from those demons but hated the picture quality. Way too blurry & unfocused.