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.
Hilarious in Hindsight: The books begin in approximately 2011. There are computer-controlled cars that drive themselves with on-board voice operated internet access, and the "link" device which hooks over the ears, acts as a cell phone, video camera, has internet access, and is voice operated. Considering some of the technology today, neither of these advances sounds out of place.
Nightmare Fuel: Arguably the whole point of the series. Listing it would be tantamount to listing the details of the story.
The main character watches as the Earth is destroyed, in extravagant detail.
Look up Heironymous Bosch. A series of his paintings are the only security system necessary for the Tower, and they're chased by nearly every Body Horror and Hybrid Monster in the paintings. Also the unmasked Reapers, or Tamara's Baby, which is Nightmare Fuel long before the readers find out just what it is.
Selective Squick: Scholastic has this in spades. People getting eaten alive by worms? Fine. Getting trapped in a painting of hell? Sure. Cannibalism? No problem. Tate being a lesbian? BLASPHEMY!