Welles starts his film with a pin-art representation of another of Kafka's stories "Before the Law." I don't think that there are many directors out there today that realize how much mood must be established in the first few minutes of a film, especially when you're dealing with a dramatic piece. Welles does understand this, and understands the power of his own voice as he narrates the story. He says that “Before the Law” is theorized to be the logic of a nightmare, and that the same theory is applied to Kafka's "The Trial". I've never seen an introduction to any film that is at all like this opening. It is visually and contextually completely unique, and unsettling. It may seem tempting to plow right into a Kafka story, throwing the viewer off immediately, but Welles prepares the viewer before-hand, and the film is all the better for it.
Anthony Perkins plays the protagonist (John K.) in "The Trial", and I am forever confused and saddened when I think that Perkins ended up being type-cast for the latter part of his career in endless Psycho sequels and movies like "Edge of Sanity". Perkins was a rare talent. He was completely convincing in any role he attempted, and seemed to delve himself entirely into any role he was given. Even though the circumstances that happen to John K. are disorienting (to say the least), Perkins has the ability to allow us to understand his characters' motivations, and allow us to sympathize with his decisions. It is one of the great movie rolls.
Perkins, in conjunction with the brilliant camera work, and the twisting, existential storyline make "The Trial" as unique and beautiful an example of movie-making as Kafka's words made “The Trial” one of the great novels. Welles plays with the perspective of his camera, from wide shots of huge set pieces, to having characters come directly at the viewer, to flying out in extremes of emotion. The plot may be confusing, but it's supposed to be. It may be frustrating to watch, but again, it's intentional. A film adaptation of a Kafka book should try the viewer's patience, because that's in the spirit of Kafka's work. If you don't want to be challenged, then look elsewhere for your entertainment.
There are those out there who bemoan "The Trial", and hate the liberties that Orson Welles took with the story. I am of the view that a movie should be different from the novel, as long as it keeps its spirit alive. A film adaptation should be a companion to the book, not a replacement. Welles wasn't a perfect filmmaker, but he went beyond perfection with "The Trial". It is one of the great films of all time.