It certainly reeks with period atmoshpere. Also, the Ray Wynstone character of the chief constable is a nice study in a man who is outwardly brutal and ruthless, but also has a tender side, which is brought out by his fish-out-of-water proper Victorian wife.

However, if you aren't into beheadings, spearings, shootings, stabbings, and exploding heads--and you like your movies short and to the point, then perhaps this isn't for you.

I didn't actually time it, but it seemed awfully long and frequently tedious. It was also unrelievedly grim and ponderous.

So, for historicity and period flavor, I would give it an "A". For general watchability, a C+.

Cheers,

Walter