Tess is a girl who seems to care about everything and everyone but herself. She has her reasons, that are slowly introduced to the audience. The movie keeps jumping between her horrible present and her horrible past, and it almost seems as if the creators want to test the limits of their protagonist: how much can she (and the people watching these scenes) bear before she is completely broken.
The cinematography is great, the acting is credible, and so Tess is definitely one of the better movies of this genre. The storytelling is a bit like in a 19th century novel, but I guess the creators wanted to make sure that 99% of their viewers fall in love with the protagonist.