I don't know a lot about Chris Marker or his extensive filmography; all I've seen is this one short film he made in 1962. You may have heard it referred to as the inspiration for Twelve Monkeys. While that's true, it is rather a bad idea to write La Jetée off as a rough draft for that movie, or for that matter to write off Twelve Monkeys as a rehash of La Jetée. They share a few key points but beyond that they are quite distinct from one another.
La Jetée is about a man "marked by an image from his childhood." It takes place in the near future, after World War III has irradiated the surface, where experiments are being done underground to send an emissary through time to seek help. I won't reveal any more of the story because you are already either familiar with it or don't want it spoiled. While it is certainly an interesting story, the best part of the short is it's composition. La Jetée is a "Photo-roman", a sort of guided slideshow, composed (almost) entirely of still black-and-white photographs. From the apocalyptic opening scenes of broken buildings in bombed-out Paris to simple pictures of a couple walking through a shady jardin, the photos are always well composed and reveal more, I think, than film might have in the same context. Not that I have any means of comparison. However, Marker avoids a sort of sci-fi audience disassociation problem (showing too much) with the time travel by only sort of implying it. Instead of the protagonist walking into a big swirly ball, the shots alternate between him lying in a hammock underground in the lab with shots of peacetime fields, children, and the woman he is destined to meet there.
In the middle of the movie, there is a series of shots of the woman dozing in bed, close-ups of her face. Birds are chirping outside, and the shots see her progressively shift her position. The bird noises multiply and compound upon one another and become louder and louder. Then, in the last shot of her face, she opens her eyes and looks up at the camera. This one piece of motion is easy to miss - there is a similar thing done in Blade Runner that I just noticed, years later - but it is very powerful, especially when she is suddenly replaced by the smug experimentor's face. I know it is available on VHS at some places, and on DVD, but the DVD version has English narration which looks to be pretty bad. I rented it several times, tried to buy it, and ended up downloading a very good copy which I will burn to my own DVD sometime soon.