One of few heavily modified book adaptations worthy of the source material. I wish it had been longer - but if that's my only complaint...

Rating: 10/10 (7 September 2017)

I was not disappointed. It was a lot truer to the spirit of the book than the 1990's miniseries. It didn't shy away from the violence or horror, the kids were allowed swear, and Skarsgård's Pennywise puts Tim Curry's performance to shame.
There was actually a lot changed from the book, but all of it was for the better - most of it, apparently, for the sake of taking advantage of the film's opportunities for better visuals, where it succeeds wildly. It's the first film I've seen with genuinely disturbing moments/visuals since Enter the Void. A few plot points are also changed, but that ended up being a plus, since you don't know what's going to happen even if you've read the book, and it's all done well.
My only complaint is that a lot was omitted - some of it, probably, because it wouldn't have translated as well to the silver screen (like the scene with Mike in the field with the bird), some of it because it was, almost certainly, unfilmable (like the infamous scene with Beverly), and most of it because of time constraints. The upside to this is that it's action-packed and much faster-paced than the book, but I would have liked if the movie had been allowed a longer runtime. Might have worked better as a trilogy than a two- parter, actually.
But if my main complaint is that it was so good it left me wanting more, there's really nothing to complain about at all. Excellent film, can't wait for the sequel.