Too long and gets repetitive
I was yawning and so were a couple others when by the time the gang got down into the well. I think 2 hours or 2h15m would've been fine. Just felt a bit too long.
They played out the clown scene way too many times. The first few times was good and creepy but then you're literally expecting it when they switch to the other character attempting to retrieve their artifact for the voodoo magic crap. Pennywise wastes too much time playing with his victims just to eat them, especially after they separated themselves to retrieve their memory items.
CGI is fantastic for the monsters but loses the vulgar and creepy effect the more you see them.
I liked the times when Pennywise does his creepy moments (eating the gay dude by the river, eating the girl with the birth defect under the bleachers). Leaves a mystery to him and how he lures his victims in and actually kills them instead of the other times where he's just spooking them or chasing them with disfiguring effects.
The one funny scene was where grown up Richie and Eddie had to choose between 3 doors (Not Scary At All, Scary, Very Scary) and there was that cute little pomeranian before the surprise.
Of all those issues, I still enjoyed the movie. I like it when Pennywise turns his victims inert when he opens his gaping mouth to show the deadlights while turning his victims eyes pure white.