It's a kids show, so it's fine that there's a 'Sarah Jane Adventures' style episode every now and again.
All the 'exploring the nature of the Doctor' type stuff was understandably put on a backseat, in favour of a jolly 'Robots Invaded My School' themed romp. Even here though, there were a few interesting reflections of the Doctor to enjoy: I liked the 'Doctor as a Caretaker' idea..... a grumpy old fellow muttering away as he fixes every leak and infestation. The Twelfth Doc fitted straight into his Groundskeeper Willie role in a way that I can't imagine his predecessors doing quite as comfortably. (I can't remember what role Ten adopted to infiltrate that school in the K-9 episode? Supply teacher? Ofsted Inspector?)
I also liked the fact that the Doc and the schoolgirl clocked each other as fellow 'disruptive elements'. I hope that she stays and doesn't become just another one of those random children that Clara kidnaps for use as accessories in a single episode, before abandoning them again, like she did those kids in that awful episode featuring the zippy Cybermen.
And of course it's fine to set the whole thing in a school - this is a well worn theatre of horror for most kids - but again, everything faltered when we got to the monster, which was easily the dullest robot I've seen in a long while. I can't even remember why it was there to be honest..... why did they need it? Everyone knows the form here: The true unheimlich source of horror in this sort of school-based lark is, of course, the teachers.
And of course, for my children, in reality, the truly terrifying part wouldn't be teachers as vampires or blood-sucking aliens or whatever - that's all a well-worn trope in this sort of drama. No, the true horror would be...y'know....two teachers like.....snogging....