The movie follows the life of a donkey - Balthazar - and the people he comes in contact with. Bresson makes it a classic - some saying Balthazar incorporates the stoicism and taking on the sins (and punishment) of others as a metaphor for Christ. Whether that is so or not will remain to be judged by each viewer but the beauty of this overall relatively tragic story is that neither Balthazar, nor Marie - one of the owners and the female protagonist - see themselves as victims. They endure.
The story gone through in a relatively short movie is amazing and the cinematography, music / sound effects are simply astounding, as is the symbolism of the movie. In spite of the message of predestination, drudgery of life (both for the donkey and the humans coming into contact with it), difficulty of adolescence etc. Bresson still manages to sneak in the odd humorous moment (the painters renting out Balthazar describing action painting).
This is not a happy movie and does not make for easy watching - as mentioned by the other reviewers Bresson did not shot movies for commercial success. But the movie is strangely fulfilling nevertheless, and one can return to it many times - something that will make you discover new elements and get a deeper appreciation of it every time you see it. In that sense it is a true masterpiece of cinema and something definitely worthwhile having on DVD.