I actually thought it was pretty bad. The teaser promised us something that never really happened. I was expecting a creepy monster of the week episode, but we got something entirely not that
The story was all over the place, and made no sense.
There were a few good lines, and a few good moments, but the rest was just...ugh.
And I really wish the doctor would stop insulting Clara on her appearance! It's like a creepy old man trying to re-assure himself that he's not turned on by the hot young lady, when it's the exact opposite. It's mostly just mean, though, and serves no point in the story.
MaryAnns review explains pretty much how I saw this episode better than I can:http://www.flickfilosopher.com/2014/09/doctor-blogging-listen.html
I thought it was trying to have its cake and eat it too. It was trying to be a scary monster of the week episode but also be deliberately vague and you're right, it just ended up not making sense.
I agree with most of your friend's critique, but this - "• Let’s talk about the unintended creepiness of having an episode revolve around the Doctor bluffing his way into a home for vulnerable children in the middle of the night." is reading too much into it.
As for Capaldi, he is the best doctor since the show came back in 2005.