SPOILERS DOWN THE PATH; THE DISCUSSION BELOW WILL NOT BE COMPREHENSIVE WITHOUT IT.
TREAD CAREFULLY. YOU'VE BEEN WARNED.
Based off another notorious antagonist in The Conjuring Universe, The Nun is a spin-off with the titular character's origin on narrative mode.
Set prior to any of the events happened thus far in the franchise, we're brought to 1952 Romania with a fresh setting. The abbey was a cool location for lore infestation. And here ends everything positive about The Nun.
With a thin and fragile story, the makers have fooled us into thinking there's more than mere jump scares here. Cheap and fake jump scares after jump scares will continue to pursue you from start to finish. Even the simplest things had loud sound effects behind it, because that's apparently what the team thought horror was after all.
What you'll also witness is characters walking around. Yes, just walking around. From one place to another. From beginning to end. No changes in characters. No changes in plot. Simply them characters walking around. What else could you do to stretch an almost non-existent material for 2 hours? As a result, it's eventless throughout the runtime.
Most of the proceedings we see onscreen were predictable, but this is not an issue exclusive to The Nun. We've been watching horror films for more than a century, thus predictability and clichés are unavoidable. But, what frustrates us actually was the lazy writing. No motivations for the antagonist. No reasons for the unnecessary backstories. Characters committing stupid mistakes. Random books found in a dug hole became tools to solve the story problem. And we could go on and on!
Admittedly, there were a few takeaway scenes. Protagonist's first encounter with Valak at the locked doorway causing dizziness and camera turning upside down, Sister Irene (Taissa Farmiga) circled for sacrifice by ambush, herd of nuns with covered faces and the live corpse at graveyard were effective moments in the movie. Also, the evil hymn soundtrack was noteworthy.