I quite liked this one as well.
If you think about it, the story isn't a new one. Tech following its programming to extremes and the result being harmful to humans has been done at least twice in Doctor Who (The Empty Child; Girl in the Fireplace). Then again there are often repeats of themes in DW; The Idiot's Lantern and Fear Hear could easily have come from the same 30 second pitch.
If we hadn't had the bit at the colony in the pre-title sequence, then this episode could have continued straight on from the previous one and been for most of the time a two-hander between The Doctor and Bill. That is not an easy thing to pull off, and I can't think if it has been done before (Babylon 5 had an episode that was just two people in a room for 45 minutes). Would the episode have worked better if we didn't know what the robots had done, and so came across the mystery at the same time as Bill and The Doctor? The downside of that is that we wouldn't know how dangerous the robots could be as the only other on-screen death is near the end of the episode.
So, lots of banter between Bill and The Doctor. She learns more about him, and we get a bit more about the promise and the vault (not much though). Nardol is the party pooper though.
Unlike the last two companions' first trip away, Bill isn't instrumental in saving the day and The Doctor.
So, the Doctor resets the robots, but what is there to stop them just doing the same thing as before? Well, The Doctor has made it that they aren't a slave race programmed to ensure everyone is happy. He talked about rent, so they are now employees of the humans as such. Hopefully the humans and robots can work together.
Next week is the Thames Frost Fair. Is this the same one The Doctor took River too? Shame we can't have a cameo appearance from River.