Not the most original Dalek story, but it's brilliant fun. The Daleks are at their most evil, with the pepperpots having cooked up deadly bacteria, and the Thals get an interesting development from their 60s days, with them being decidedly more violent as opposed to pacifistic. However, it's a shame that the story doesn't use the concept of invisible Daleks presented in this story more, as it's a really strong idea that's abandoned early into the narrative.