Here are my thoughts on the movie (no spoilers):
There's something very wrong with Derry, and it's not just the thing that looks like a clown. Is it a malignant presence within its people? Is it the place itself? History is brought up frequently as an important element of the plot, but IT never feels all that interested in exploring its most interesting narrative conceit beyond perfunctory exposition. It doesn't seem all that interested in a cohesive narrative structure either, and its attempts at using the characters as mouthpieces for its themes are...cumbersome, to say the least. No, IT's interests really lie in making a gang of losers you enjoy watching, and in throwing a barrage of horrific vignettes assaultive enough to make a crowded theater lose their collective shit. If my crowded preview screening was evidence enough, it succeeded handily in those aims.
The cast of young actors they assembled are clearly capable of being a likeable ensemble. Finn Wolfhard of Stranger Things fame has already proven himself on the small screen, and he gets all the best laughs here as the mouthy Richie. But besides their surface level ticks, the losers never really felt like characters to me. They have a lot of banter and the occasional tender moment, but while the movie takes its sweet time setting this gang up, in doing so it never bothers to tell us much about them beyond their surface ticks. That's because, much like The Conjuring series, IT treats many of its "scare" scenes as almost stand-alone sequences, that really less on eerie tension and more on grating noises and toothy creatures bum rushing the camera. That's not to say that neither the gang nor the scares work, because the best moments of the film come from some unexpected stylistic jolts as the group bonds, capturing their outsider status and endearing them to us at the same time, and the funhouse approach to horror leads to some really enjoyable sequences that are impressive not necessarily because of their craft, but in the gleefulness in which it chains together gruesome horrors in relentless fashion. The best compliment I can give the film is that at some point it flashes by a cinema marquee advertising a Nightmare on Elm Street sequel, and IT would feel right at home in that series (and not as one of the worse entries).
And of course I have to mention Bill Skarsgård's Pennywise. His performance has already garnered the lion's share of prerelease attention and it's not for nothing. His slobbering, gutterly gleeful take on the clown makes for a worthy mascot for the film, and though he doesn't get a lot of screen time he clearly makes the most of every minute.
Ultimately IT's heart is in the right place and will likely lead many an audience member to laugh and squeal as they sit through this haunted house ride of a movie. But I can't help but imagine what might have been if it spent less effort trying to get immediate and predictable reactions from a crowd, and more effort crafting a nightmare that lingers and festers in the dark spaces of your head like the thing that haunts Derry. Less in your face and more in the gutter. It's certainly good weekend fun, but a 27 year burn this is not.