The idea is entirely believable that some college students could be so desperate for a place to live that they would ignore the obvious red flags. They take false comfort in safety in numbers when they move into the “too good to be true” lodging, and well, we know what happens next. We don’t even need the requisite nighttime thunder and lightning to set up the spooky mansion story, but it is a nice touch and it doesn’t take long for Bill and the Doctor to be looking for clues and answers.
The easy chemistry between Capaldi and Mackie makes me wish she had been around longer in the series. When she introduces the Doctor as her Granddad in this episode, it is just too funny, especially in light of how strongly he objects to the designation. That the TARDIS is employed as a moving van is also a nice excuse for a chuckle.
In terms of the MOTW, the alien lice were creepy enough, but nothing substantial was revealed about them. It would have been helpful to know where they came from, how they got there, and whether or not they were sentient. I’m glad the students inexplicably got reconstituted, I guess, but that took the menace out of the story for me and lessened the impact.