Stephen King has long excelled at portraying dysfunctional relationships, and It, no surprise, is full of them. The history of Derry, Maine, going back centuries to before the city even existed, is full of people being awful. The people there have always lived on a Bad Spot*, intensifying how awful many of them are, but it's a matter of degree: as King has said, "Damaged people damage people," and It shows this. King has empathy for the bullies, who've been hurt themselves, but doesn't flinch from showing how they hurt others. But bullying due to love gone sour appears, too: Eddie's mom reacts to the loss of her husband and Eddie's father by trying to make Eddie scared of the world and even of his own body, and simply can't hear anyone challenge her. Any challenge is a personal attack, she feels (she doesn't really think it through), so she hurts and hobbles her son as a result. Not fair, but she'd never understand that.
Racist attacks, spousal abuse, gang justice, ignoring of said bullying, possible violent sabotage, gay-bashing (handled weirdly by King; he's long been a little off about how he handles non-hetero sexualities in his work), all co-exist among the supernatural threats of this novel, as King's work often does: the unbelievable and the all-too-believable. Pennywise the Clown, the frequent form of that supernatural evil (It Itself, in other words), wants that, feeds off of it, and can encourage it. Pennywise being fictional doesn't leave us off the hook for how we treat each other. And there is so much of that, what with 1100 rollercoaster-y pages. Had I read this when I was younger and more likely to re-read books, I probably would not have re-read this.
I'm glad I read It, but I immediately wanted to read something much lighter. (That's Myth Alliances by Robert Asprin and Jody Lynn Nye. I'm also working on the second Dresden Files, but the book isn't really grabbing me and at this point I'm mainly reading it just to have read it.)
* My very-much-not-inner science fiction fan did appreciate the science-fictional explanation of why Derry is like this.