I found It to be a major let down compared to CC. I play ghost only, so I should have been right at home...
The first part was...ok, I'm not a fan of puzzles though really. The second part was the worst for me though. It felt more like a maze than a city. Canals with few ways of mantling out of, dead-ends everywhere, far too confusing of a layout.
The museum was the easiest part for me actually. I got the vault done and dusted pretty quick. The marble everywhere was just annoying thou...