The good: The first appearance of the Cybermen is chilling, and the first regeneration of the Doctor is thrilling. Good sense of tension throughout, and Cutler is the kind of foe I love to hate.

The bad: If it weren't the first Cyberman story or first regeneration story, it would fall flat. Thrilling as it is in execution, it must be admitted that the Doctor doesn't exactly do much about the Cybermen, just lets them gorge on Earth's energy until their planet goes kerblooey. They did stop the launching of the Z-Bomb, admittedly, so it's not as though they didn't make an impact, but the Doctor was completely asleep for that.

That said, I still love it a lot; you just have to be willing to look at it through the lens of a viewer of the time. 8/10