Wasn't sure I'd like it...
Thought it might just be another period piece filled with filthy folks, prostitutes, gross illnesses and murders. This HAS those things, yes, but they aren't the centerpiece. The writing is terrific. Well acted, well paced and atmospheric with a fantastic underlying metaphysical mysteriousness and historic tidbits. And that's just after watching the first episode!
And it doesn't hurt gettin' to watch Tom on screen the whole time!