In Their Nature is back to just being solid fun, not as reference heavy as the first three, but getting to be on the front lines of a Rutan/Sontaran skirmish is great, and the TARDIS team getting caught by both sides in turn is just classic Classic Doctor Who.

Honestly the more I see of Sontarans in the expanded universe, the more I'm starting to really like them, their sense of honour shines through here, and Five comparing them to the tale of The Frog and The Scorpion is a really interesting view of them that I like a lot.

Also get to see more of what's going on in the bigger picture of things which is fun!