I've heard one person claim that in every successive adaptation of the story (Novel, Manga, then Anime), both Tanya and Being X become increasingly unlikable, with one seemingly being made worse to keep up with the other.

As someone who has only read the manga and watched the anime, much of the appeal comes from the fact that Tanya is not exactly an entirely calm and rational person, despite her efforts to be so.

Having read the light novels, I can say that nearly all of the edginess is gone. Tanya comes off as highly rational and her libertarian views are made much clearer. Most of her inner monologues are griping about her job, how war is a waste of human resources or how useless people should be gotten rid of. Also aside from the first book Being X is essentially absent.