What The Trial lacks in comprehension (purposely at that) it makes up for in cinematography, set design, art direction and music. Essentially a nightmare tale, Joseph K. slowly comes to madness as his accusation for some unknown crime leads him into the abyss of a legal system, full of strange, abusive, mysterious, confusing people.
As a film I couldn't sit through it at once, I had to get up and return a couple times because the convoluted situation makes it hard to follow. This aspect is surely purposeful, Welles is a master of storytelling and images, and the production itself proves amazing.
I would highly recommend this for it's adaptation of Kafka's posthumous story, beautiful and horrible direction, cinematography, set and art direction and music.