This film is up there with all of Miyazaki's works, including "Spirited Away," "Princess Mononoke," and "My Neighbour Totoro."
It has a very surreal quality and a deceptive cuteness to it, which may trick you into thinking it trite or superficial. However, like some of the best Anime out there, "cute" can leave you open to some horrifying consequences. Obviously it's not as heavy as "Grave of the Fireflies" or as light hearted and uplifting as "Totoro", but this film lies somewhere in between. I haven't read the book, but I'll bet it's similar in theme and scope to "Le Petit Prince" by Antoine de Saint-Exupéry.
I'm certainly not a Christian, and often tire easily when confronted by blatant Christian imagery in film, literature, and music. However, this film requires a degree of spirituality to get its point across, and the Christian images present, while overpowering at times, represent a nebulous kind of spirituality -- as if it's saying "there is a force out there which helps determine our fates, but I can't define what it is."
For example, the film takes place in some alternate European world (most likely Italy) and the characters have Italian names. But they're anthropomorphic cats and don't appear to practice any kind of Christianity (they celebrate moon festivals, and sail lantern boats in the river). However, they later meet up with human children on the train, and listen to Christian hymns on the wireless ("Nearer my God to Thee"). They pass several different layers of Heaven, and Giovani, the main character, has a special ticket that allows him passage to "the one True Heaven".
The film, like the train, takes its time to get where it's going, and some powerful messages come across to the viewer. Unlike many Anime and Western films, this one does not end with a happy and neatly tied-up ending, nor does it take pains to explain the things that go on inside the train. It leaves that to the viewer. This is what makes good art films. This is what makes a film worthwhile.
