Frustrating approach to its villain. But generally, an enjoyable story. The aquatic setting is really interesting and well realised, and used as a good backdrop to explore another side of the Eighth Doctor. The amnesia and forgetting Lucie is interesting, however, a little rushed with little consequence within this story. Its nice to find a world the Doctor was so intent on protecting after the time dedicated there, which was a nice approach to develop and strengthen this Doctor's character.