The movie is one of the first color animes, which came out in the 1950s. It's a trip and a half. For the most part, it's just a fairy tale: a white serpent is transformed into a woman, a boy falls in love with her, and a sorcerer tries to break them up because he knows what she is.
But one of the best parts is when the sorcerer and the snake-woman decide to have this magical space battle. I'm not exaggerating: the two of them are kind of floating around in some kind of black void (he with his crystal ball), shooting various colors of light at each other. Everything up until that point is pretty normal, then BOOM! Early Chinese space disco.
Despite that oddity, it really is an excellent movie. It's a precursor to modern anime, and you can see a lot of history from this one movie. Give it a shot - you will especially enjoy the musical bits.