I don't think anything can prepare you for what this is. I suspected there would be something wild afoot, but even that didn't prepare me. What happens is actually pretty insane and creative, but the execution of it is so ridiculous that you just can't take it seriously.
Given how cheesy this movie was at the start and knowing James Wan was the director, I figured they had to be in on it and doing it intentionally. But as the film progresses, you realize they're actually playing it completely straight and it's honestly just that bad. This movie really isn't scary either which was surprising.
The camerawork is big highlight and the over-the-top 80s music was pretty fun. You can tell Wan was trying to make a throwback here, but he forgot the self-awareness that's necessary for movies like this. I know some people are saying the camp is intentional, but even if it is, it could have been executed far better than this.
I will give Wan credit for creating a truly original horror film that actually surprised me. Whether you like it or not, we should applaud more filmmaking that takes chances and doesn't completely give away what a movie is about beforehand.