Overall Series 10 was a very good series of stories about the Doctor and the changing circumstances that his meeting with Bill Potts brings about. It isn't a simple story (or series of stories), but there are many repeating themes. And then there are the bookends. As an example, Heather's becoming the Pilot is one of the main plots of the first episode, and she appears to rescue Bill and the Doctor after the defeat of the Cybermen on Floor 507. Her appearance in the latter episode may seem to come out of thin air, but it is set up in the first.
One of these themes is memories... Bill's memories in particular play an important part in various episodes. The Doctor gives her a photo of her mother, and it is that memory of her mother that allows her to defeat the Monks (even if that plot thread was weak). In addition, the strength of mind that allows her to hold out against the Monk's 'fake news' field is what allows her to resist the cyberconversion. A thread through the later part of the series is Missy remembering those she had killed...
Another is the phrase 'Without hope, without witness, without reward'. It appears in Extremis, and also in The Doctor Falls. In the former it is linked to the Doctor rescuing Missy from the executioners because he considers her a friend. In the latter, it helps to swing Missy back to the Doctor's side. It also appeared in some of the other episodes, but these are the most prominent. The development of the various characters through the series was also good. The Doctor is shown to be 'chafing' under the responsibility of guarding Missy.
He is clearly interested in Bill's development, encouraging her to look outside the box, with examples of such occurring throughout the series (even at the end). His weaknesses are also shown, quite well, especially after he's blinded at the space station, and hides it from Bill, with dramatic consequences! (See below for more.) He seems to be desperate for Missy to turn to the good side, and is flat flooted by the appearance of her predecessor on the colony ship. This aspect was also quite well done.
Bill's development was also interesting. She continues to ask questions in every episode (even of 'Razor'). It doesn't get too much. Her savvyness is also well done (except for in Empress of Mars, where it may be a little thick). Overall she was an important part of the storylines, with her mental fortitude helping to defeat the Monks (even if she caused them to take over the planet), and the Cybermen, The former may have seemed like a cheat, but the latter was a lot better done. Nardole was done well aslo.
There was more to him than first met the eye. But it was the storyline involving Missy that was the best aspect of the series. The earlier portions regarding the Vault may have dragged a bit, but after the 'Monk's trilogy' it lead to a very interesting conclusion. Was the Monk's trilogy a mistake? I'm not sure. The Lie of the Land may have been a let down, but the earlier portions involving the Doctor's weakness were done very well, so probably not. Overall, despite this dip in the middle, it was a great series.
8.5/10.