The only drawback being that the aliens' M.O. is just a bit too close to the Christmas episode aliens. How many different buggers are there now searching out folks at the end of their lives? We've got these witnesses, the Christmas bunch interviewing everyone before they die, and the Teselecta from Let's Kill Hitler trying to execute people just before they die.
This may have worked better as a pure historical. Not sure we even needed the aliens this week.
Oh, and just like any good woman raised in the early 20th Century, when a husband tells his wife we're abandoning the family farm and making a run for it, she dutifully obeys. Not very PC in the early 21th century, but not impossible to swallow that Yaz's nan would flip her position so quickly if ordered by her husband. So on this point I don't have a big quibble with how the writers kept the plot going so quickly.