The first one, "Space Babies" was alright, but felt too childish. "The Devils Chord" didn't hit for me because they just didn't have the budget for really being able to explore a higher level being of such power.
But Boom? Boom can be defeated by one simple question. "Where's the Sonic?"
It's never addressed, the Doctor never asks Ruby to go get it from the TARDIS if he doesn't have it on him. And it's never even explained that if she could go and get it, it wouldn't effect the landmine.
It's basic questions like this, that need to be answered in an episode like this. It would have taken a total of 4 sentences to cancel out the Sonic. But they never even mention it.
That's just bad writing right there.
Plus the Doctor's dialogue felt like it belonged more to Matt's Doctor than Ncuti's and DEAR GOD, Moffat cannot write children to save his life.
I'm hoping the season gets better because they're 1.5 for three with me right now.
Episode three started very strong for me (even if it did have the usual sledgehammer-to-the-head subtlety in its political messaging), but when Splice arrived at the landmine it went downhill so fast. Started with a really good premise, well thought-out logical steps of why everything happened as it did.
But in the second half, they just kept throwing more characters and more BS at the problem and trying to pull on audience emotions instead of telling a good story. Like, how does the Doctor holding a corpse mean it's connected to the Internet? I am holding my phone and touching a microwave - is my microwave now connected to the Internet through me??
And gotta agree with OP, Moffat has apparently never met a child in his life. She must have the strongest faith ever to not even flinch after her dad dies. But hang on - why did she go looking for dad if it doesn't matter whether he dies? And why was she upset when Ruby died?