By far one of my favorite season openers, you have MI-6, going undercover, creepy aliens, James Bond style story beats, and the Master! All the actors are top of the game on this episode, including Sacha Dhawan, playing a wonderfully unhinged Master. Even though I knew about the reveal at the end, I think it's one of the best surprise reveals in the show, you don't expect it at all.

To the negatives, I do think the Master reveal was a little abrupt. The Doctor breaks apart a small bit of his cover story and then he decides to just abandon his cover. Though, it seemed like it was part of his plan to reveal himself then anyway.

Also, it wasn't clear what happened to the billionaire guy in the plane? He just disappeared and a bomb was there instead.