When I imagined what might happen in this episode, The Doctor time hopping through history chasing after (or maybe running from) The Master certainly wasn't I expected. In a small way, I wish there was a bit more of that time hopping but that probably would've overstuffed the episode and it was better to focus on Ada Lovelace and Noor Inayat Khan. It's a shame that The Doctor is suddenly wiping memories of historical figures who encounter her when that wasn't so much of a concern in the past (what with fixed points of time and otherwise general proclamations of the inability of changing time). I wonder what Mary Shelley would think of this development (an Eighth Doctor reference).
As for the overall scheme of the Kasaavin and The Master, I have to admit I'm a bit disappointed how basic it turned out to be. It's not too surprising their goals were originally different before The Master came along and he ended up using them like he's used other races in the past for his own schemes, so I don't mind that development. However, considering the initial mystery behind the Kasaavin's nature and how they took their humanoid form to mock us, they disappeared into the background as mere henchmen in this episode. I hope that we get to see them again in another episode (not necessarily this season) without The Master so they can be better developed.
Lastly, I gotta say I'm not all that keen with this new season arc development. The Master has always had a thing against the Time Lords, long before the sound of drums, so I don't question his motivations, rather his ability to wipe out of the Time Lords. I really had hoped that he was pushing The Doctor's buttons on the Eiffel Tower but then The Doctor did a quick trip to Gallifrey (funny how easy it is to travel there again) and saw the truth for herself. As for the great big lie The Master is crying about, I kind of worry it's something along the lines of Lungbarrow (but not necessarily Lungbarrow itself). And really, how much of the fundamental basis of the Time Lords is Chibnall willing to change (but I guess the same could be said about Cartmel...).
I'm certain we'll see The Master again this season and I'm looking forward to Sacha Dhawan once again. His take on the character is still a bit all over the place, but I particularly enjoy his cool collected persona as we saw when he conversed with Barton and again with The Doctor on the Eiffel Tower.
Speaking of which, Barton got away so I bet we'll see him again, too...