Just got around to watching this last night.
@Anushka Mokosh has more or less covered my feelings.
It was one of the better episodes - but that's not saying much... The initial intro was fine - particularly because the way it was shot (with the voiceover) it appeared that the enemy was a humanoid. But why split up the Dalek instead of burning it? And what happened to its shell (it was shown in that old book that Mitch had? And on that point, why wasn't it taken more seriously - as, perhaps, a depiction of the Dalek itself would not be (being not so recognisable. I also doubt the guy in Yorkshire would have ended up buried, with the Dalek fragment; he would have been left where he lay and probably eaten/torn apart by animals.
The love interest between Mitch and Lin was fine as it didn't really distract from the episode, but the re-introduction of Ryan's father was dreadful and padded out the episode.
The Dalek taking over Lin's body was good - though I struggle to accept she could possibly lift two large cast iron gear wheels. But it's actions were contradictory; no compunction in killing random people (fine; Daleks have no compassion) but not killing Lin when it was finished with her?
Good that a single Dalek was a threat - though that was some laptop Lin had...
The UNIT joke was pathetic as was the cutaway to the internet-less family.
The segment with the soldiers was out of place (unless I missed something).
They allowed random (and nice) people to be killed but then chickened out at the end by allowing Ryan's dad to be saved - in the rather mediocre ending.
Overall disappointing, but not as much as the rest of the series.
My wife thought it was good but that there was too much "touchy feely" stuff - as with the rest of the series and wondered if that was deliberate because she was a woman and so it would be better to take this line (she hoped not).
And I take back what I originally said about Yaz; at the start of the series I thought she was good (and pondered the idea of a Doctor/Yaz pairing (losing Ryan and Graham)) but since then she's proven to be as ineffective as Ryan, and it's Graham that has come though.
2020 is some time to wait for another series (and I suppose it will be late 2020). I'm not expecting much to change unless Jodi leaves (
not because of her, but because changing the nature of the scripts would mean changing the way the Doctor is, and it would be difficult to justify doing this with the "same" Doctor). Also the audience figures disagree with my opinion...