I haven't actually seen this show. But these clips about the show, particularly Sondheim's explication of how he wrote, are fascinating:
The play opens in a fairground shooting gallery where, amid flashing lights, human figures trundle past on a conveyor belt. One by one, a collection of misfits enter the stage, where the Proprietor of the game entices them to play, promising that their problems will be solved by killing a President. ("Everybody’s Got the Right"). Leon Czolgosz, John Hinckley, Charles Guiteau, Giuseppe Zangara, Samuel Byck, Lynette "Squeaky" Fromme, and Sara Jane Moore are given their guns one by one. John Wilkes Booth enters last and the Proprietor introduces him to the others as their pioneer before he begins distributing ammunition. The assassins take aim as "Hail to the Chief" heralds Abraham Lincoln's offstage arrival. Booth excuses himself, a shot rings out and Booth shouts, "Sic semper tyrannis!"
http://en.wikipedia.org/...
I think watching/listening to Sondheim discuss how he writes is even more interesting than watching his shows, although the two are of a piece.
This, for example, previews the current dialogue about guns:
Why they did it: