The series of films and anime was built on an interactive novel published by TypeMoon. In which through different reading path and interaction the main character Shirou Emiya would end up in a romantic relationship with a different female lead. Each season of anime or film focuses on one route of the ending a novel reader would end up with in one of their read through. This movie is the second part of a three-part film that focuses on the relationship between Shirou Emiya and Sakura.
What is constant in all these parallel universe endings is the endless fight amongst masters and servants in pursuit of the holy grail. The larger questions revolve around why magus chase the holy grail, what undying wish these historical heroic spirits have they want to realise so bad that their ghosts linger in our world, and the ultimate questions what is the holy grail and is it worth it?
In order to really appreciate the delicate story lines this series have woven, in particular this second part of the Sakura story line, viewer is advised to gain prior knowledge of the settings of each character in this fictional universe. Because the way the stories are told is in a way that all characters' retain their history and backgrounds, only in each different alternate universe they interact differently. Basically viewers are watching the same period of time in a universe with different historical event turnout.
Other than that, it must be said, answers to a lot of the major questions the whole Fate/Stay Night franchise has built up are getting slowly revealed. There is a real sense of satisfaction in learning those answers. Comparing to Evangelion series, Fate/Stay Night reveals its plot in a very well thought out and methodical order, with a back drop of philosophical and existential provocation, and not handled heavy handily like EVA does. No preaching, which is always a plus to Japanese anime since their characters usually monologues a lot.
Visual wise, the character design may not be everybody's cup of tea. But the scenes are absolutely stunning and the fighting sequences are edge of the seat style breath taking, because the story makes you care about the characters. It is a must see for the fans. And to anyone wants to get into the series, you won't be disappointed.