Episode 3: as Rose's first date continues, the Doctor takes her into the past. The TARDIS is running even rougher than before, and all these two adrenaline junkies do is laugh about it. Hello! How long's this craft supposed to hold together?
The story is a Dr. Who staple: a period costume piece with a 1950s-style "alien technology disguised as the supernatural" story. It's distinguished by how well the historical characters are fleshed out. Both the writer and the actors did an excellent job there.
We also learn that the pinpoint navigational system is still broken. The Doctor aimed for 1860 Naples and landed in 1869 Cardiff. Why Cardiff? It's not the sight of the location shots, and they're doing plenty of other "on location" stories in Cardiff. They could have set this one somewhere else.
The pacing problem with the climax seems to be worked out. Now they need to work out their more subtle pacing problems as well.
As far as the sub-plots go, we learn the name of our Great War, the "Time War", that a lot of "higher races" died in it, and that this episode's guest species lost their bodies in it. A psychic mentions that Rose has "seen the Darkness and met the Big Bad Wolf." Dunno who the Wolf's supposed to be. The Doctor? He has to be the bogeyman for dozens of would-be conquering races. If Daleks had children they would warn them, "Eat your peas or the Doctor will get you!"
In classic Dr. Who tradition, these are villains who will return. In modern TV tradition there were 3-4 subplots worked on in this episode that will return as well. That's one modern tradition that dovetails nicely with the Dr. Who universe.