If you're going to have a film that mocks the plot of horror movies, even 1980s horror movies, you need to have a reasonably rock-solid plot yourself. And there are some gaps here. I spent the first half of the movie assuming Gertie, Alia Shawkat's character, was Max (Farmiga)'s aunt, because while Shawkat is great in this and I want to see her in more movies in general, she is playing high school age, or freshman college--ditto with Tom Middleditch. You can kind of squint and make the case that this doesn't matter for DeVine, Akerman, and the rest of the 80s crew, since they don't have to be believable as teenagers so much as it needs to believable that someone in the 80s would cast them as such, but for the modern group, it doesn't work. The actors are, again, great, but the roles they're playing could use some re-definition.
The other problem is the emotional core at the center of the movie. In the movie within the movie, Akerman plays a scream queen, whose role is to lose her virginity and die horribly for it; in the movie at large, she's also Max's mother, who gets killed in the first scene. A lot of the film is devoted to the daughter working through the mom's death through interactions with a fictional character that looks like her mom. It's kind of a clumsy set-up: Nancy, the in-film character, has to be elastic/shallow enough to bond with someone she just met, but real enough for Max's emotional struggle to matter, AND fit in as a stock horror trope for the film within the film. It takes a lot of hoop jumping to make it happen, and I'm not sure it works. A better way to go about it, I think, would have been for Akerman as Max's mom not die in that first scene, go with them into the film, and be forced to replace Nancy after she accidentally dies too soon, to keep the plot going.
There's a lot of little logic jumps too, where the plot's compromised to make a joke of questionable quality--that's the peril of trying to be a meta-horror film and a comedy. But there's also some really coo bits, both meta and otherwise. The moment where the modern group realise that they're about to meet Max's deceased mom is wonderfully creepy (and would admittedly be a loss if they changed it to my suggestion), and the first half of the fight against the slasher is really cool as it threatens to go against and in their favour. On the meta level, finding out that the entire film universe loops every 92 minutes, being caught up in a flashback, and I can see the humour in trying to restrain the ditsy oversexualized character (Angela Trimbur does a real fun job with the role, putting a lot more into it than it really deserves), even if it doesn't quite get there.
It's not a bad movie, and it does the aforementioned meta-horror/comedy mix better than, say, the entirety of the Scary Movie franchise. It's not as good as Cabin in the Woods, though it fits light popcorn film a lot better. It has some strong performances from really great comedic actors. But I'd be lying if I said I wasn't hoping for more. There's room for more play, and more critical play, than what's here.