I played this mission this afternoon and boy this was a very good experience! This mission feels big and mazelike but is very smart designed, you find the objectives any path you choose, and most important you are not running in circles. After almost 3 hours of exploring I was tired but satisfied that I could complete everything. I liked the most the atmosphere which reminded me of The Sword OM in Thief 1. The story was good, but it could be more detailed, I wonder what was the story of that Constantine like mansion where the hiding place is. I mean Garret's landlord must be a very strange man..
There where also other parts of the city that are turned upside down like in The Sword mission, there must be a story behind this, but maybe it is and I missed it when I explored the mission.
Anyway overall this was a great mission, I rated it 10/10 and I strongly recommend it!