I didn't see the twist coming, that the Master is Indian. Yeah totally didn't see that one coming.

It harkens back to classic Who of the Pertwee era, like how where the Doctor acted as UNIT adviser, this time recruited to help MI6. It also has classic Who tropes such as the Doctor telling some wild sounding story about aliens and daring you to challenge the narrative. It reminds me of the time Tom Baker's Doctors would say that. In this case, its Whitaker's Doctor accusing one of the suspect villains of being in league with the aliens. You can tell the character knows she is onto him, but tries to brush it off by accusing the Doctor of being insane. Oh, and it also ends on a nice cliffhanger like classic Who.
There are some contrived flaws of course. Like why did the runaway car at the start pause a while, giving the Doctor time to come up with a plan to take control of it. Why did they need to shoot the head of MI6 when these teleporting aliens can just come and kill him? It however doesn't detract from the episode.
Now since this is part one, could it have problems in part two? Yeah. There are some signs which are very gimmicky IMO.
For example the Master cryptically saying "all you know is a lie." All I can say is, the payoff for that better be good.
The other gimmicky thing is these aliens with languages which isn't recognised and hints they are from another reality. OMG, some aliens which even the knowledge of the Time Lords don't recognise. Its sort of like a Worf Effect, but knowledge instead of fighting. Of course a simple reason the language isn't recognised is that its simply a new constructed language, since you know, the theme of the episode is spying. I will have to see the second episode.
All in all, a fun episode and looking forward to episode 2.