Start the clock. 

Experimentation is the heart of Doctor Who, but the lungs or some other important organ would have to be the ideas.

This is a traditional formula made fresh and exciting with audacity and confidence. It knows it's ideas are excellent and lets the insanity of what it's doing distract from it's technical efficiency. You aren't thinking this isn't going to actually be good, you're distracted by the pulp, the presentation. The show knows exactly what it is doing here though, and this is a plain showcase for Capaldi and Coleman at the top of their game.

Feels like the kind of episode that would benefit from a Target Novelization, but I'm obsessed with what we have anyway.