The first half of this season set such a high standard that a certain final disappointment was downright inevitable. Yet the valiant, spirited progress makes for engaging watching, even if the ultimate conclusion seems slightly obvious (only slightly!). This season has a distinct fatalistic edge, reclaiming a level of darkness unseen on DW since "The Horror of Fang Rock." All science fiction dramas should aspire to this level of witty, mordant insight.
For one, Matt Smith is finally breaking from playing a version of David Tennant. Though he retains Tennant's rapid-fire verbal tendencies, Smith shirks the attitude of using humor to cover rage. His Doctor runs more on guilt, and his journey has the feeling of exile and penance rather than meandering. He makes this clear in the first episode of this half-season, when several successive holograms of past traveling companions send him into a spiral of self-recrimination.
Russell T. Davies suggested the Doctor was somehow responsible for the chaos surrounding him. Margaret's monologue in the episode "Boomtown" stresses that, to his vanquished enemies, the Doctor is the real criminal. Steven Moffat takes a more nuanced tack: while the Doctor holds some culpability for bad choices, he's the product of a violent and conflicted universe. In such a setting, the show suggests, a good man has little choice but to lash out in the name of justice.
Observant viewers will spot how the conundrum introduced in the first half of this season will be resolved in the second half, if they pay attention to the episode "Let's Kill Hitler." The resolution, while earned, does seem a bit pat, and that's disappointing, considering how the series has striven to boost our expectations. Yet the conflict leading to that resolution is anything but simplistic. Not since Andrew Cartmel has anyone tried such ambitious themes on DW.
I did not care for Season 5. I thought Moffat got off on the wrong foot. But I can see how that season set the stage for everything occurring here. This psychological realism and existential dread in a science fiction adventure setting first drew me to the original DW when I was seven, and I joy to see it reinstated, and taken to new heights, here. This half-season is what Doctor Who should be about, and I can't get enough.