While many of the supplements do deal with the film itself, many of them are about Bletchley Park and the Enigma machine itself. This film was apparently a pet project of Mick Jagger's, and it is his Enigma machine that actually appears in the film. The film is very much a tribute to Touring and the staff of Bletchley Park, who were, indeed, unsung heroes of World War II, and one of the main pleasures of the film this time around was taking in the setting, as great pains were taken to make it historically accurate.
I really recommend the film. It is a great mystery, with excellent performances, and the operation of the Enigma machine itself, a fascinating piece of technology, is an essential part of the story.
Dougray Scott and Kate Winslet have to rely upon their intelligence to solve the enigma of Enigma.