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.
Mood Whiplash: Replica Stu's scene in the movie is pretty funny, especially when he yells out "DO THE LIMBO! HOW LOW CAN YOU GO?!" while chasing the heroines with Combat Tentacles.
Nightmare Fuel: Practically the whole book. Koontz is usually big on environmental and atmospheric description, and he uses it to uncomfortable advantage here. Some of the scariest bits involve Jenny and Lisa's initial exploration of the empty town, even before they find more bodies. The Take Our Word for It deaths of many of the soldiers also serve to make them more horrifying than it would have been if he'd shown it.
Trapped by Mountain Lions: Any chapter containing the character Fletcher Kale. It's made even worse by the fact that, with the exception of the first chapter he appears in and the final epilogue chapter, he never interacts with any of the other main characters at all, and nothing else in the story would have been affected if his character had been cut. It's hard to find the escape of a murderer sociopath the least bit compelling, or find the character the least bit menacing, given the Eldritch Abomination everyone else is dealing with several dozen miles away.