The Beast of Orlok is a fun and exciting horror romp through the Schwartswald.
At first, I found the light tone a bit weird, seeing as it was clearly going for horror - a carriage, attacked in the dead of night by a horrible monster lurching from the shroud of the trees - that was until I realized that this story is a send-up of the Golden Age of Horror, with oodles of camp, horrifying monsters, devious schemes to upset the natural order of society and pearl-clutching wives one horrifying revelation from fainting into their husband's arms.
If you see it from that perspective it is really, really good fun, I could honestly see Moffat doing an episode like this - y'know, in a good way.

8/10