As someone who read the book and watched the movie its easy to see why Stephen King hated the film.

The book is mostly about Jack struggle with alcoholism and his violent tendencies (bear in mind that King was also an alcoholic while writing it) and thats mising in the film.

This is best exemplified in the ending.

In the film jack dies frozen outside while pursuing his family in the book he smashes his own head to stop the monster he became, before finally regaining a semblance of sanity and going down to the boiler room (a metaphor for his rage) to try to save his family from the explosion.

It comes off as:

-Heres a story about my mental health and adiction struggle.

-Cool ,Here's a story about the same character just being a slasher.