Characterization needed a lot of massaging - it's not enough to say "cultists" and make them weird crazy people when we have to watch them for the next hour. There's only three of them so I should know why every one of them is willing to die for this cult or why they want out. If we don't need to know them that well, we also don't need them onscreen for 75% of the film.
Riley Scott and the character Josie are terrific: Scott has the cocky humor when it's in the script so she should get more of an opportunity to use it. There's enough of an underdog hero aesthetic and an amusing basis for her to have a near-superpower set of abilities but ultimately, she's underutilized. The setup is basically a Lovecraftian take on Die Hard so we kinda needed a lot more of that. It's cultists and a rich guy's house not Nakatomi Plaza, so we could have totally been treated to some really brutal "Home Alone" shenanigans but ultimately there just wasn't enough to work with.
Fight scenes are pretty good, the acting was decent - would have probably been a lot better if there was more to work with on the page. The premise is solid but it felt like they rushed the script.
I'd watch a sequel if they wanted to really go with it. More numerous cultists, or really eff a handful of them up by the end, Harry and Marv style, and play it for laughs. This felt too timid to be as good as it could have been. Funnier, bloodier, creepier... something.