Konrad, in the Dark Mod you receive a Stealth Rating after the mission is finished. This is calculated by how many times (and how severely) you broke stealth in the mission. I.E. a "first alert" from a guard gives 0 points, but a "second alert" gives one and if they see you and chase you, that gives 5 points. So the lower your stealth score, the more sneaky you were.
As for the mission I have to agree that the visuals were very well crafted and the town felt alive. Immersion was high and ...