I have a love/hate relationship with Clara, especially after her utterly shallow reaction to the Doctor's regeneration at the beginning of Series 8.
Kind of saw where this ep was going early on, when I wondered why they didn't deal with what turned out to be the solution when it was clearly the key to the episode the first time they encountered it.
Fascinated by the Doctor's refusal to bring Journey Blue along because she's a soldier. We keep running up against violence vs non-violent solutions as a major theme this series, and we're only two eps in.
And, of course, who's Missy? (I see five possibilities: (1) The Master, reincarnated female (others have already noted "Missy"<--"Mistrress"); (2) The Rani (less likely, I think); (3) The Valeyard (possible but not as likely even as the Rani); (4) an embittered, empowered Clara (so far what she's done is consistent with the powers of, say Souffle Girl); (5) something else. We DO know that she has some way of keeping track of the Doctor, and some way of retrieving his victims from oblivion (I suspect a transmat just prior to death in the case of the human; rebuilding the robot is a far less difficult matter).
Okay. Enough for now.