Just finished the main quest and I agree with Rendrassa. The last main quest feels like a petty steep drop in writing quality compared to what came before. For all the build up, the final boss is nothing more than a whinny boy wearing daddy's too big suit. His sister being a villain and mastermind behind the whole thing is an interesting twist, but I feel it needs two or three more quest to flesh out. And how they just give all the information to the player so all the collaborators get taken out with one fall swoop than everything's sunshine and flowers just feel too tidy and convenient.
I can understand why player gets promoted to the head of the Order. Since if there's a post main quest plot it needs to account both ending which is twice the work. But with how it ended it feels like the story ends on a whimper instead of a bang. Crossing my fingers some kind of quest modding tool or guide will get released later, because I think the setting of this game have more millage for a post main quest storyline.
What I think would be interesting for a post main quest story-line with Order/Good ending, now the evidence there's a conspiracy group of human supremacist, and the ineffective of the Order got exposed, non-human extreme members within the order use this as an excuse to start an anti-human campaign to topple human from ruling class.