There is brilliance in Mr. Langella's performance, but perhaps more importantly there is brilliance in Doug Hughes' direction of Mr. Zeller's work. The vignette blackouts, the shocking strobe light, the stark lights up on the next, often conflicting scene - all effects that heighten the impact of the material.
What Mr. Zeller does so brilliantly is bring the audience into the world of confusion and uncertainty of Andre by repeatedly swapping actors for the same character - to which the audience in addition to Mr. Langella must react and process. He juxtaposes dialogue that is similar but with entirely different outcomes. He repeats segments of dialogue between the same characters but offers different emotion and conclusion. The jolting effect to the audience is what a man in Mr. Langella's condition must experience in his condition.
Mr. Langella does most of the heavy lifting here, and his performance is transcendent. This is one play you won't soon forget - even tho the play itself is all about forgetting.