Ignoring what I think of the adaptation.
The series is written very, very well. Honestly, once D joins the Green squad the story finds it's rhythm and doesn't let up imo. The very mystery of the series is probably its strongest aspect. As it adds more and more wrinkles. It really gets you thinking

. Like you think you are on to something, but then you doubt yourself and here comes another wrinkle. I need to get back to reading it, put it on pause on 100 chapters.
Negi is a really talented writer. The fact he wrote this coming off The Quintessential Quintuplets solidifies that. Considering how different the genres of the two series are and both are done well.