How is Pennywise rushing at the screen not a jump scare? I thought you were giving the impression that the movie relies heavily on jump scares, due to that aspect and "modern horror"
Pennywise rushing at the screen isn't generally played as a jump scare in my opinion. It happens too often and I think it looks silly, but it's usually fairly well telegraphed. Maybe because a couple of them were present in the trailers I had a sense for when they were going to occur. Perhaps others may disagree, I just didn't see them as a traditional jump scare with a large music crash etc. I recall jumping at the movie maybe twice and neither time was Pennywise rushing the screen.
The aspect of 'modern horror' I disliked most was the overuse of CGI and the tendency to show everything on screen in great detail rather than leaving things to the audiences' imagination. I think horror works best when you show just enough to scare but not so much that the fear is lost. For example, I actually enjoyed the first maybe 30 minutes of Insidious but once it showed the guy properly and you knew exactly what it was and it showed it in great detail all the time thereafter, all the tension was sapped out of the movie for me.
With IT, it renders a LOT of stuff front and centre in rather middling CGI and I think much of it would have worked better implied or partially obscured/in the shadows/whatever old school horror tricks you care to think of. There's one scene in particular I have in mind when I talk about this and it's Stan's fear. Good idea, really poor CGI execution, would have worked so much better if much more had been left to the imagination. My distaste for CGI is not necessarily about the quality of the effect, it's about the way many directors use it as a way to show everything on screen when it is very often not the best approach for the genre. Just because you can doesn't mean you should etc.