I LOVED "The Idiot." LOVED it. From start to finish, from the performances to the story to the score to the set, it was thought-provoking, touching, and completely delightful. Much of this can no doubt be attributed to the amazing story by Dostoyevsky, which is a fascinating exploration of human psychology, society, and above all, human nature. The adaptation for the stage was very effective, I thought, and while the idiosyncrasies of Russian nomenclature were occasionally daunting, the result was far less confusing than it had potential to be.
The performances, particularly those of Tom Truss as Prince Myshkin and Smaranda Ciceu as Nastasya Filippovna, were phenomenal. I was really able to believe in the prince and Nastasya as people rather than characters on a stage, and that made the story all the more heartbreaking.
From a playwright's perspective, it's difficult to know what decisions were made by the director/actors or the person adapting the script from Dostoyevsky's novel. One choice that I thought was very good, however, was the way many scenes (or single detailed scenes) from the book were seamlessly condensed to a few minutes on stage (Nastasya's almost-wedding to the prince is a good example.)