Writing this just after seeing the episode and not seeing anything else, I have to say this was on par with the Tesla episode as a more than acceptable example of modern Doctor Who. It was a little uneven to being with, and the Captain Jack section seemed forced, unnecessary and far too lense-flarey, but the whole Ruth Doctor angle was curious and interesting, and an example of Chibnall finally trying to claim a story arc of his own.
As before, it's incredible how much more effective Jodie's performance is allowed to be by unfussy, cool, patient direction. As with Telsa, the script was slower, more considered and measured, more personal. Gone was the hyperactive, incessant exposition by Jodie, in favour of a calmer, more mature story line. Hopefully they get the message now that less is almost always more.
No spoilers, please, for anything that comes after that I haven't seen yet (my family watches about 2 per week).