To me, this episode has more thought put into it than any other. I’ve wached it soooo many times, and it’s one of my absolute favourites! I also love how it has more of a detective feeling than most episodes, and it just seems more real and believable since the main character is not the Doctor, but played by Sally Sparrow. The Doctor is this otherworldly, all-knowing, bone-chillingly smart man on an easter egg, and it brings a new feel to the episode as WE discover the Doctor, and it’s the not the other way around where the Doctor is trying to figure everything out.
The time alterations are difficult to wrap your mind around definitely, it’s just so complex and un-ending as the universe itself that I’ve given up trying to put it into words x)