Given the title of the episode, I thought the latest Doctor Who episode would be about River Song. Boy was I wrong. Neil Gaiman wrote the episode and he decided to delve into the character of the Tardis. Strangely enough, I've been mentally writing an episode that did the same thing, for some time. Neil Gaiman's take was completely different than mine, and roughly two orders of magnitude better. I guess that's why he's a world renowned writer and I'm not.
Suffice it to say that I absolutely loved the episode although I had to keep pausing it and replaying bits to get all of the dialogue, some of which I found hard to make out. Its also quite evident that Neil Gaiman has got to be completely mad (in a good way) in order to be THAT creative in his writing.