I happened upon this CD because I knew some of Marc-Andre Hamelin's Sorabji recordings and knew that he concentrated on virtuosic repertoire. Rzewski was new to me, but even on a first listen it was abvious that this series of variations for solo piano is a substantial addition to the piano repertoire. Although no one would mistake it for a nineteenth century piece, it is far from avant garde and there is plenty here that links it to the main canon of such works.
Stylistically "The People United ..." embraces many different styles, so it is arguable that a genuine "Rzewski" voice is difficult to identify, but the distinctive nature of the Theme, together with the ingenuity of scoring, results in a work that has more coherence and variety than you might expect. There is very little pastiche here - no Straussian waltzes or Bachian fugues - so most of the playfulness has to be generated solely by the exuberance of the pianistic writing, which is quite stunning .... not least in the contrapuntal series of variations from 19 to 23.
Subsequently, I bought the Nonesuch Rzewski boxed set which includes the composer's own performance of "The People United ...", and Hamelin's is to me superior both in recording and performance. Having listened to that set I also think that "The People United ..." is by far the best introduction to the composer's work since it holds in check some of his more idiosyncratic tricks. As it is, there are short passages of whistling in "The People United ..." that will not appeal to everyone.
The fillers on this disc - two of the four "North American Ballads" are, it should be added, excellent and make a compelling argument for purchase on their own. I'd urge anyone with any interest in piano repertoire - even if their interest usually stops with Chopin - to give this disc a chance.