I think this one's pretty fun. The one disappointment for me is that the story sacrifices all its complexity by making the Gelth generic evil monsters. The moral question of reusing the bodies of the dead is an interesting one that the episode ultimately doesn't have to bother reckoning with because it turns out the Gelth really suck. It's the rare twist that makes the story less compelling. It's already pretty twisty to do a zombie body snatcher plot where it turns out the snatchers aren't evil, so pivoting back to them being evil again is just a bit boring.
Otherwise, I like how the episode makes good use of a historical figure. They can sometimes feel a bit hit and miss, but Dickens makes for a good one-off companion who doesn't suffer a major character assassination, etc. It is mildly weird that we have two episodes in a row where a one-off companion burns up (Jabe last week, Gwyneth this week). I wonder if more thought goes into episode order in later series, just to avoid stories echoing each other's plot points. It's not really a problem, but you wouldn't want to turn it into a pattern.