I have a cartographer's mind, so once I do some mental mapping, it's not as annoying. Still, the cathedral prelude -- all those ruined buildings with tunnels, multiple layers, rope ladders, sluices, etc. -- do complicate things. Not that it's a bad feeling or anything; in fact, I kinda wish there were more modern games like this out on the market. Dishonored kinda fits the bill, I guess, to the point that Garrett voices Corvo (IIRC).
Take me down from the ridge where the summer ends
And watch the city spread out just like a jet's flame