This is a fun enough idea in and of itself. Shrinking and travelling into a Dalek is pretty cool, and the best part of this episode explores Rusty's character, how it relates to the Doctor, and what a "good Dalek" even means. Some of the designs around the Dalek's interior are pretty interesting and I do love those shots of the Doctor face-to-face with a giant Dalek organism more than I don't. That stuff is largely great, but it feels like a very Moffat-heavy episode, even if he isn't the only credited writer.

There are some really strong, memorable lines in this story from Rusty, but for every one of those we get awful ones from the Doctor. He goes way too anti-military here and it is only done for the sake of drama with Danny Pink down the road, and the whole "Clara is my carer" thing is just not a funny line and makes Twelve seem worse than what feels natural for his character. This won't be the last time Moffat pulls this questionable feat, either, which is frustration because Capaldi always deserved better than that.

The way the story hypes itself up at the beginning, calling the inside of the Dalek "the most dangerous place in the universe," is one of many ways this story holds itself back. Even just how ham-fisted some of the writing can be at certain parts of the story really bothers me, like around the soldiers or the introduction of Danny Pink (which was pretty awful and only made worst in hindsight knowing what is in store for that character).

Finally, while I enjoyed the morality struggle between Rusty and the Doctor, it definitely gets overdone at a certain point and I found the ties to the larger narrative of the season about Twelve not knowing if he is a good man a little clumsy here. It's an alright story, but not the best. Basically just an inferior version of Dalek, really.