Overall, the episode wasn't terrible. It had some good moments between Bill and the Doctor (though I don't know how to respond to writers when they place words in the Doctor's mouth that are patently false, like "I've never had the luxury of outrage"); it had a compelling "mystery"; and its supporting cast was pretty diverse (though I do find the abundance of children in the Capaldi era to be super annoying). The episode was, to be sure, basically a rehash of previous nuWho episodes except in a different setting -- "The Beast Below" comes to mind, what with the feeding of people to a humongous creature imprisoned beneath the city for some exploitative purpose -- but that's par for the course for Doctor Who these days.
But following the handful of articles about how Doctor Who was supposed to "tackle race and whitewashing" in this episode, I did find it to be disappointing. The episode definitely did acknowledge those topics, but there's a difference between "acknowledging" a thing and "tackling" it. (This distinction, by the way, is part of the reason I declined to comment more publicly on Get Out. I thought the movie was an effective thriller, but I found its much-lauded exploration of racism to be a letdown -- especially given the well-meaning posts from some of my white friends to the tune of "all white people need to see this movie.") With respect to whitewashing, the subject is dispensed with in a 20-second exchange. Explicit racism gets a bit more emphasis, if only because the episode's villain responds to Bill with a cartoonishly racist outpouring before the Doctor socks him in the face. And while I guess that response represents progress -- the last time a character was openly racist to his companion, the Doctor proceeded to fall painfully in love with that character -- the episode's "tackling" of the topic is restricted to that one bit of dialogue. Also, having the racist character be the kind of villain who brags about his lack of even "an ounce of compassion" sort of precludes a serious examination of racism in its more insidious and pervasive guises. And the response to slavery and historical discrimination in Doctor Who continues to be downright infuriating -- when Bill points out that she's black and that slavery is still legal in that time period, the Doctor instructs her to visit the wardrobe and pick out a set of appropriate clothes, because of course that will fix everything. (When Martha voiced the same concern, Tennant's Doctor responded, "Well, I'm not exactly human. Just walk round like you own the place, always works for me." Yes, he might be an alien, but the Doctor should know that that approach wouldn't "always work" for someone who doesn't look like a white male.) It's actually not unlike the attitude of some folks today (frex, far too many of Bill O'Reilly's monologues) -- if those blacks would just pull up their pants and look decent, people wouldn't treat them poorly. It's uninformed and insulting to say the least.
I also continue to be annoyed by the feel-good yet nonsensical conclusions to these episodes. Here, the Doctor gives Bill a choice: they can destroy the creature imprisoned at the bottom of the Thames, or they can choose life and let it go free -- even though there's a risk that it might continue to eat people. The episode doesn't press the analogy, but given the (exceedingly quick) mention of slavery toward the beginning of the episode, it's clear that choosing to free the creature is analogous to the historical decision to free African slaves: yes, whites had some misgivings and weren't really sure what would happen, but they ultimately made the correct and more compassionate choice. African slaves, however, didn't fucking eat people. This thing had been chained up in the Thames for as long as anyone could remember (the villain's family had kept it for generations), and during that time all it had ever been fed (they were lured out onto the ice, at which point it actively hunted them) was people. So it eats people now; people are its natural prey. And somehow, after the Doctor spoke passionately about the value of human life -- and, I should add, had no problem with the bondage and slaughter of "lesser" creatures (he didn't balk at the elephant in chains and happily tucked into the various meats served up at the festival) -- the right choice is to set this people-eating horror free? I guess I get that Doctor Who these days wants its episode endings to strike super optimistic notes (even when doing so makes no sense; I found the conclusion to last week's ep especially baffling), but sometimes tough decisions need to be made. I miss Harriet Jones.
At any rate, it would certainly be possible for the show to attempt a more involved treatment of race, slavery, and the whitewashing of history (in fact, I kinda expected the monster to be eating black people on the directive of some future time fugitive who was baffled by the presence of and therefore intent upon removing these individuals who weren't part of his record), but I don't think Doctor Who as written is really up to the task... and I'm torn between wishing it would try harder and wishing it just wouldn't try at all. I mean, when the show is willing to commit to an episode that isn't properly "fun," it's capable of better -- see "Vincent and the Doctor," which, while still flawed (and admittedly a little insulting to someone with experience with these issues), represented a much more respectable attempt to address depression and suicide. If a Doctor Who writer were serious enough to take that kind of approach with racism (etc.), it might be possible for the show to somewhat satisfyingly "tackle" the subject.