The small details in the game are incredible.
Act 2 non-story spoilersI love that not only can you meet Kniles' mother, you can explore his room, and even find the graves of his sisters who died under mysterious circumstances. All of this for a character who IIRC isn't even linked to an actual quest.
Yeah, there are a lot stuff like that. Like there are a lot of notes that reference future NPCs and whatnot and you only notice them on replays too. The game has a lot of sub-plots and random NPC connections, It's really something I appreciate.