The previous System Settings UI was long overdue an update. While the new UI does very much resemble macOS, I don't see that as an issue, as it works very well in this context. At least, I believe it does, but I am no UI/UX expert.
I've never been able to find what I needed quickly in the old UI, always felt disorganized and random. I like the one on the iPad a lot better, I find it way easier to navigate, so I'm happy for the change.
So yes, it functioned poorly, while also looking terrible by today's standards.