I felt this was true until 30 hours in, but after that, it starts feeling much more repetitive. Smaller ideas are stretched much further and IMO they're not nearly as exciting as the beginning ones.

Fair enough, it has definitely evened out now that I've completed the 4 base stories. Reaching the Antipode though has certainly ignited some motivation, I want to figure out the red areas, and getting into the deeper AxB areas is still interesting and I suspect I've got another 20 hours of that to go at least.

I felt like that in the demo. It's waaaay too slow to do anything difficult. Basically everything in the hour or so that I played was trivially easy.

Compared to Baba Is You which gets difficult and interesting after like 10 minutes.