Look, I think it's dated. Very dated and spoiled by pop culture. I tried to find a single review from a critic in the last 10 years of the film that wasn't lapping it up about how when they were 12 at some dinky theater this was the scariest thing they'd ever seen and it still holds up after the 10th rewatch and I couldn't.
First of all, it's not scary at all. It's just kinda boring. The first hour of high school is terrible after the opening scene which is well done. Then, it doesn't even feel like a full movie, but a short story/short film. I mean it's literally These are the characters -> Ok prom night -> ending. Like a 3 scene film. There's basically no subplots besides Carrie and her Mother and nothing else to the story. The problem is that the prom night has been spoiled to hell in pop culture, so even though I hadn't seen the movie I still knew what was going to happen at the prom. So it's like an hour of boring dated 70s high school film, then you get the prom scene and it's incredibly tame and not freaky at all by modern standards. Then you get the ending which was ok.
I'm not joking when I say I probably would've liked the 2013 remake more (I watched the trailer and it looked basically shot for shot identically) just because everything wouldn't be so dated and goofy and maybe there'd actually be some tension.
Then again maybe not. I can't really see how the film could ever be considered scary to anyone, even back in the 70s. There is no bad guy, no monster, no evil force, no evil ghost, there is nothing bad to be scared about in the film besides the crazy evil mother. But crazy evil mother is so overdone it's laughably ridiculous like a satire of hyper religious people. She also barely gets any screen time, but then almost no one does because it's basically a short film in content. I couldn't tell if we were supposed to be scared of Carrie when she's the only likeable person in the film.
There's some nice shots from a directing point of view, the dancing scene with the camera spinning the whole time, the slow motion climax of the prom, the opening scene and the ending scene in the house. The split-screen stuff during the climax of the prom bits was creative but I also thought it was pretty lolz. But maybe that was just because watching people die in hilariously goofy 70s ways doesn't work anymore as anything but a comedy. Plus you're rooting for Carrie the whole time, so how can it be scary when you're like yeah fuck up those jerks!
It's a weird movie. I see it working as a coming of age thing dealing with religious upbringing and bullying, but I just don't see it ever working as a horror film at all. I'm curious if it would have been scary if I had read the book instead since books don't date like movies. This is why I'm skipping the 1970's Salem's Lot and just reading the book instead. I want something creepy and 70s films aren't gonna give it to me.
But then again I re-watched The Shining not too long ago and still felt it held up. Then again that might be bias having seen it for the first time in the 90s. Same with Nightmare on Elm Street/Halloween/Friday the 13th. In my mind those are all still spooky, but then maybe that's because I watched them as a kid and today someone watching them for the first time as an adult would just laugh the whole way through and be bored. It's hard to judge films that you saw long ago.
Yet when I watched a bunch of Hitchcock I hadn't seen about a decade ago, I still was impressed. Then again they weren't really scary, but thrillers and maybe thrillers hold up better.
DUNNO