You know, in hindsight, I think I liked Luke Rattigan from Sontaran two-parter so much because I'm also very autistic /hj

Osgood is always a delightful character to center a story on, and this glimpse into her early time at UNIT really doesn't disappoint. The Grey Archive in concept is already just a brilliant idea, it has a very SCP vibe, which, given the original SCP was inspired by Doctor Who (probably), just feels really nice. Osgood is written suitably autistically (/hj), and I love the little glimpse we get into her home life here as well, more information about (and interaction with) the older sister mentioned in Day of The Doctor is just fun.

The small nods there are occasionally to other areas of the Whoniverse are always a delight, the anti-grav (anti-mav?) device that Osgood uses being the ones from Victory of the Daleks is just a fun bit of continuity, of course they'd end up in UNIT's posession.

And the Clone PoV stuff is also really nice. In generally I always like it when stories answer "What happened to that thing from that story", so the cloning chamber being used here is already great, but then the fact that we get to see through the leader clone's eyes, see how he thinks, and get the eventual reveal that this more human clone is a clone of Luke Rattigan. All of that is just so so good.