I loved the fact that Twelve gets to offer someone a jelly baby (he offered one in a cigarette case in his first season, like the Fourth in Face of Evil, but this time he was actually able to say it). I like it because, really, more Doctors should do it, there's no reason it should be so married to the Fourth--the Second was actually the first to do it--and I also liked it because it was like the Doctor taking the line back from Simm's Master who used it in one of his Russell T. Davies episodes.
Nardole (Matt Lucas) had a couple nice moments and his goodbye was good though it mostly made me wish more time had been taken to develop him over the season to earn his protestations about being likely to sell children on the black market.
One could say Bill's resolution is very much like Clara's only taken a step further--like Clara, Bill has died and been reborn and has gone off with another woman to have adventures, only Bill's relationship is explicitly romantic. And really sweet. I wish there'd been more build up of a relationship with Heather (Stephanie Hyam) but her appearance and the role in the resolution was so cool I'm willing to accept it. Now they're both water and, as Heather tells Bill directly, change has become for them something easy and fun and under her own control.
I wonder if the appearance of David Bradley at the end was prompted by leaked set photos from the Christmas special. It made me curious to see how this unfolds, in any case. Bradley isn't that much like Hartnell but at least he's a good actor.