I loved that episode and Peter Capaldi might have my favorite line in the show, when he was talking about the calories in the TARDIS not counting:
Clara: You're Kidding
Doctor: Of course I am it's a Time Machine not a Miracle Worker
This episode was like Doctor Who meets Ocean's Eleven Meet's TNG's Alligance. It was a lot of fun and I didn't see the reveal coming. I also was reminded of End of the World (The very first episode of Doctor Who I saw) in terms of quirkiness and just fun. This is my favorite episode of this series so far, and I think I'm now fully on the Peter Capaldi train. He's a great doctor with some witty dialog and an insane attitude.