I have never read a Stephen King story and did not see the previous incarnation of the movie, so I saw IT: Chapter One with almost as open a mind as anyone can have. That said, I do not like horror in general and am easily startled, so I saw the film with some trepidation.
Fortunately, I did not need to worry as IT was a horror in genre only and had zero moments that startled. Rather, IT was a coming-of-age story better described as graphic young adult (YA) with all the attendant overwrought melodrama.
Without giving much away, the story revolves around the disappearance of a number of kids in small town Anywhere, U.S.A. With a growing group of friends, the brother of one of the missing kids look for clues to the disappearances, only to be haunted by a malevolent clown called Pennywise.
Although the evil clown is the titular IT, the movie is more about the bond that forms between the kids and the slow realization that they are stronger as a group than on their own.

The demon-battling Loser’s Club make this more YA than horror
For me, this is where the movie could have been so much better, because the bigger evils in town were the day-to-day horrors these kids faced, forces as malevolent as Pennywise but insanely more powerful for all their normalcy. If anything, the clown was simply a metaphor.
To their credit, the child actors brought depth to the otherwise trope preteen outsiders—the skinny kid, the chubby kid, the African-American kid, the loner girl, the bespectacled smart-ass nerd, the Jewy kid and the whiner—and their connections felt real. It also helped that they had some really funny lines to take the piss out of each other.

Clown horror weakened by everyday malevolence of kids’ lives
But this is where the film was more YA than horror. Rather than probe deeply into issues of bullying, sexual predation, grief management or drug-doping kids into docility, the film instead tapped into its inner Goonies, almost completely removing the horror.
A decently constructed film, performed well, the thing you need to fear the least is turning out the lights when you go to bed.
IT is just not that into you.
Pretty intense and freaky. Nice review.
Thanks…wish there had been more to the story, but accept that this might simply be the nature of the beast