The Doctor: B
In "Into the Dalek," what makes Peter Capaldi's 12th Doctor tick became both clearer and muddled at the same time.
What's clear is that 12 is a far less touchy-feely kind of Doctor than 11. He's not friendly, he's not fun-loving and he values pragmatism over compassion (can you imagine 11 sacrificing Ross to save everyone else?). He's cold towards people (see his comment about Ross being the "top layer [of protein goo], if you want to say a few words.") and he's wildly uninterested in learning details about them ("This is gun girl. She has a gun and she's a girl. This one.. is her uncle, though I may have made that up to pass the time while they were talking.")
But maybe it's okay that he's like that. The 1st, 4th and 9th Doctors were similarly dour (at least at first), and they turned out fine. At least Clara's around to care "so I don't have to."
Another striking difference from 11 is how he's very uncertain about his own morality. He told "Rusty" that it was only after he went to the Dalek home world Skaro that he understood who he truly was. The Doctor saw this mission to turn a Dalek good as a litmus test of his own goodness, and he failed the test. What Rusty learned was hatred, which implies that this Doctor defines himself by his hatred for the Daleks. When he was pleading for Rusty to see more than the hate in his heart, the Doctor was pleading for his own soul.
What's not clear is why he's suddenly so uncertain about whether or not he's good. Throughout all his regenerations, the Doctor has always been good. He's the hero of the story. The way you cast doubt on a character's morals is to have them do something truly awful, undertake some dark and terrible action, to give him a reason for his crisis of conscience. Standing around pondering your ethics in hypothetical terms doesn't justify angst.
Clara: A
The rehabilitation of Clara Oswald as a compelling character continues. Bravo for smacking some sense back into the Doctor right when he needed it. (He had it coming after all the crap he put her through last week.) That smack was the most exciting moment in the entire episode.
Clara's function with the 12th Doctor is to be his teacher, and she takes that role seriously (smack!). This was reiterated again and again. This Doctor can't, on his own, bridge the gap between humanity and his alien aloofness. So he brings her along to help him learn to do that. Note that his first instinct when faced with a moral crisis (the "good Dalek") was to fetch Clara.
The Impossible Girl once told us she "was born to save the Doctor." That's still the case, but she's not saving his life anymore. Now she's saving his soul.
Season 8's Big Bad: B+
We got barely a cameo from Missy this week, but we learned something new about her. Last week, she revived a cyborg who'd seemingly died. Even the Doctor could do this, since its body is based on technology, so no big revelation there.
This week, however, she restored life to the dead. We watched as the Dalek antibodies zapped soldier Gretchen Carlisle, a fatal action. Yet seconds later she was in Missy's "Heaven," confused but alive and kicking. (This was an echo of an earlier moment when Journey Blue materialized inside the TARDIS just as her ship exploded. Might there be a connection there?)
"Into the Dalek": C
The episode had a lot going for it, most notably some cool ideas about going all "Fantastic Voyage" inside a Dalek and the notion of a "good" Dalek. The characters were great too, peeling back layers for both the Doctor and Clara, as well as introducing the instantly-endearing PTS-sufferer Danny Pink and harsh-but-sympathetic soldier Journey Blue. (Hopefully Steven Moffat has somewhere interesting to take Danny other than the contrived "Clara has a boyfriend the Doctor won't approve of" thing.)
But somehow it didn't add up to the sum of its parts. It didn't gel, which is a common problem faced by most episodes starring new Doctors in their early days. Going inside "the most dangerous place in the universe" should have been a non-stop thrill ride. Instead it was kind of ho-hum.
It wasn't a bad episode. It just wasn't a great one.
One last thought:
Journey's request to go with the Doctor was surprising, since she spent most of the episode judging him and disapproving of his way of doing things. His rejection because she was a soldier was equally surprising.
Since when does the Doctor have a problem with soldiers? He's worked closely with them before (hello, UNIT) and even traveled with them (hi there, Brigadier). So what's the deal?
Journey would have made an interesting companion. She'd never be the happy-go-lucky Amy or Clara archetype. She'd be something more serious, more all-business. And maybe that's why the Doctor refused to take her along. She could never be his anchor or teacher the way his most recent companions were. But she had a solid foundation from which to build; watching her grow and change as a character could have been fascinating.
Hey Moff, free idea: bring Journey back when Jenna Coleman leaves the show. It worked for Donna...