These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Iron Woobie: Shuinchi lost both of his parents, is slowly going insane, and is attacked by supernatural monsters many times during the series yet still keeps trying to help
Moral Event Horizon: Prior to their transformation to a mass of hedgerows, the refugees kicked out Kirie's family out of their very own place to make space.
Paranoia Fuel: You may not want to eat cinnamon buns for a long time!
Which highlights another bit of paranoia: After a few chapters of Uzumaki, you'll start noticing the spirals all around you. Which is exactly how most of the characters start their "spiral obsession," which inevitably leads to madness, deformity, or death.
There is also a chance that if you used to be fond of snails, that fondness will stop. And if you, by accident, step on a snail or hurt it in any other way, prepare to slightly panic the following days if you see or feel an irregularity on your back (or just if you for some reason feel very slow or thirsty).
They Wasted a Perfectly Good Plot: For some, the fact that the series spends most of its time in a chapter-by-chapter format with little or no continuity is a point of frustration.
Values Dissonance: In western culture, burying a body in the ground as opposed to cremation is very common. But in Uzumaki it plays with the Japanese thought of walking ontop of dead bodies directly beneath your feet in graveyards to be deeply unsettling.