I like this serial. It benefits from being on the shorter side. The story is concise but interesting. The twist reveal is  set up nicely and done very well.

I immediately like Vicki, and not just because she looks like my favourite cousin. This is a great introductory episode for a new companion. I love how she immediately trusts the Doctor, how much she cares for the local wildlife, and her willingness to forgive Barbara despite killing her pet.

Unlike most classic stories yet to come, this serial doesn't immediately forget about Susan. The Doctor is clearly still feeling her loss. I appreciate that.