This is an odd one. It's not terrible. It had action. But it continues a very odd Dalek story. After the Human Daleks all die, I don't really feel any sympathy or compassion for them. They were still empty killing slaves, even if they have the odd moment of something that looks like empathy. As for Dalek sec, I'm glad to not have to look at the weird design anymore.
We got an answer for the green goop - turns out it was an "embryo". Given the Dalek's supposed metaphor as supremacist Nazis, it feels out of place that they would chuck any failed biology into a sewer of all places. It never amounted to anything beyond this one line. The technobabble gene editing stuff makes no sense, but I can suspend my disbelief there.
Plot-wise, the doctor's ultimate "sacrifice" is almost identical to what he did back at Alexandra Palace the previous series: Climb up the tall tower and interrupt it. Well, it works, so don't fix what isn't broken I guess. I am surprised that the Daleks, who can terminate slaves remotely, didn't do so the moment they mutinied. And that the only Dalek who can issue a wireless kill signal, needs to be physically crocodile clipped in to a computer somewhere. Those plot holes are more difficult to overlook.
Historically, wikipedia's list of solar events (there's a list for everything, I love it), tells me there was a solar flare event that affected new york May 1921. However, the Emprie State building was completed in 1931, 10 years later. It's a small detail I doubt anyone would care about, but it's mildly annoying.
By the end, Doctor ended up helping lazlo, but left him looking disfigured. Feels like he probably could have fixed him completely if he put in a bit of effort. I know the Doctor tries not to meddle too much, but this is another case where a little meddling round trip to a future hospital and back would probably be better for the timeline.
There was some little bits of humour I did enjoy:
- Doctor's slinking away and overdramaticisms at the beginning
- "[Turns to look at each other] Both: Dalekanium!"
- Martha telling someone else not to wander off