I like that in the end it was a story about the Doctor not getting involved and leaving it to Humanity to make the decision, and also his absolute trust in Clara in what she would do. Unfortunately he's a bit of a dick about it.
Which is what really sums up this Doctor. He's a bit of a dick. We've known that since 'Deep Breath', but it finally sinks in for Clara as he pushes her too far, not just leaving her to make the decision, but in an extremely harsh way with “It's time to take the stabilizers off your bike.” This new Doctor might be coming as a bit of a shock to people who are used to Tennant and Smith, but this is the Doctor.
He has that thing that Hartnell had where he doesn't quite get humanity, mixed with the side that Colin Baker gave us, of him being so much sure of himself than anyone else. Unfortunately the two don't mix that well. But along with them I can quite easily see Pertwee or Eccleston saying something similar being in a situation like that.
I also really liked that the horrendous moment, and a moment that felt like it could be what the entire episode was about, was a throwaway monster. Those spiders were a puzzle piece to get the Doctor on the path to realising what the moon really was.
That is a defining moment in the future history of the human race. One of the moments that finally got us out into the universe, which explains why we're everywhere in the galaxy, and also had a lot of similar sounding references to when the Ninth Doctor kept talking about the Fourth Great and Bountiful Human Empire. It's a clear nod to the continuing message of Doctor Who, that with time and scientific intrigue, humanity can become something outstanding special, further reinforced with the plight of Courtney. Going from a troublesome student who isn't interested in school, who couldn't cope with the TARDIS, to gaining a purpose upon going to the moon and witnessing the birth of a different species, her life hits a whole new track and will become a very important person now.
However, that ending, with the Doctor talking about the future of humanity... was that meant to be him looking at time? There were references earlier to the grey spots he can't see, but that isn't how the Doctor works. It's all knowledge, and he has to go with his what he knows versus what he sees and what he thinks is best. If we're now giving the Doctor some weird time-sense where he arrives and knows something must be fixed? I might be unhappy with that.
I also promised myself I'd stop talking about this stuff (apart from when it's someone like Keeley Hawes, who I can't not admit my crush for), but the casting of Hermione Norris is a damn fine clever move. Getting her in to play an astronaut version of her character from Spooks, a character that's cold and willing to make the hard choices for the greater good, made that character land so much better. As a Spooks fan, I'm used to her being right, even if that stance is the exact opposite to what Doctor Who ever has as a show. Doctor Who was always going to present that not blowing the moon up for a baby is the right move, but with Norris being the one advocating the destruction it came across as a viable option.
Overall, it was another 'alright' episode of Who. Like 'The Caretaker' it didn't set anything alight, it did its job. When we look back on Season 8 in time 'Kill the Moon' will be one people easily forget. But again, Jenna Coleman absolutely hits it out the park this episode. That speech at the end, along with the fantastic line of “Tell me what you knew, Doctor, or I'll smack you so hard you'll regenerate.” This is a defining moment in Clara and the Doctor's relationship. I sort of wish next week Moffat has the balls to go without her for one episode. Make us miss her as well.