Alan Cumming is back on Broadway doing a limited run of his tour-de-force almost-one-man Macbeth, and it is a must-see.  Set in a psychiatric ward, Cumming plays a deeply disturbed man who impersonates almost every character in the Shakespeare classic, occasionally leaving clues as to who this poor patient is, why he is recounting this story, and what has led him to become so tortured. 
Typically when I go into a Shakespearean play it takes me a few minutes for my ears to get accustomed to the diaalect, much like hearing a foreign language or accent and re-adjusting your listening habits. At first you found yourself doing a similar sort of thing in deciphering the various characters Cumming plays. That is, until you start noticing how he holds himself differently for each character, takes on different affectations, and that these subtler differences perfectly bridge the line between Cumming playing multiple characters and playing one madman who embodies each of the characters in the story.  It is nothing short of amazing, and when you join the rest of the audience for a standing ovation afterwards it is because of a truly spectacular performance, not because you liked the guy in The Good Wife.
I would recommend reacquainting yourself with the storyline and characters first if you're not too familiar with Macbeth, as this production adds a full layer on top of Shakespeare's text. Myself, I only had two small complaints with the show:

Complaint # 1. Towards the end, when Cumming is playing Lady Macbeth in the "out, out damn spot" scene, the lines where others describe Lady Macbeth's madness become the two asylum workers' commentary on the madness of Cumming's patient. I'm all for changed readings and meanings in Shakespeare's language, but since the lines were originally referring to Lady Macbeth, they instead continue to mis-comment on Cumming's male patient as a "she". If I presume that this particular patient's diagnosis includes Disassociative Personality Disorder--and that is a reading that may not be intended--it seems like this could be solved so simply by making the first instance of "she" more emphasized, almost in air quotes, as if referring to a side of the patient's personality.

Complaint # 2. Alan Cumming didn't get nominated for best actor? Wtf.