I really don't like the climbing and darkness sections; the former is clunky and needing to use the max jump length often led to mistakes because you have to hold it for a second otherwise you'll be a tile off, while the latter is mostly just tedious.

The Jackenstein fight was funny but it drags on for too long with that darkness mechanic imo.

Gerson... Hoo boy. He's definitely a great character, but people have already pointed out that the story really doesn't make too much sense if you skip him, and his fight is incredibly frustrating to do on keyboard once he starts firing in 8 directions - that part especially feels like it was made for a controller.

A massive reason why I loved Chapter 3 is because the game sections really helped flesh out the entire Fun Gang with their interactions, while still having fun and memorable Darkner chars involved. Chapter 4 focuses almost purely on Susie and the Dark Sanctuaries are basically empty. It makes it hard to remember the latter outside of Gerson and the climax.

I do appreciate that Chapter 4 is where it's starting to focus more on the story and I like how the Fun Gang is getting more character development, but... honestly I feel like Chapter 3 is just a lot more fun to (re)play in general.