This story has a gritty, real world feel without being overly angsty or po faced. It has a vintage "end of the wilderness years" feel.

Hex is a marvellous creation. They do a great job of building his slightly futuristic version of London (2021) and the hospital he works in. The fact Ace has a partner to flirt with is very satisfying. Hex adds a new dimension to her character. She is his mentor during the satisfyingly Doctor lite part 1. I got a proper thrill from hearing Hex enter the TARDIS for the first time and encountering a dismissive Doctor.

Like all the best Cybermen stories it has an unexpected reveal at the end of part two! The fact that the enemies were Cybermen was not something that ever struck me as a possibility, given the only monstrosities we had met before the reveal were stoic, introspective patients who indulged in sensation and feeling.

It is rare that the regularly used plot device of a human teaming up with the cybermen (or daleks, etc.) feels believable. But they nail it here - you can see why they feel justified in their approach.

This one is a real game changer.