While the other reviews, especially the one by ginz1, go a long way in describing this cd, I would like to make some additional comments on "Sur Incises".
Having followed Boulez from earlier works like the second piano sonata (get Pollini), through Structures (get the Kontarskys) and a live rendition of Incises, it was about time to see what new direction he had given to his highly developed stream of musical conscience. While "the virus" of serialism has fully integrated in Boulez' musical DNA, Sur Incises may be one of the composer's most liberated and liberating compositions.
Music as expression of ordered sound exists in time and space. Whereas the preceding DG recording of Boulez' Repons went to great length in describing the position of both performers and loudspeakers on the "playing field", space is also an integral part of Sur Incises. Together with the universe of sonorities that the inclusions of harps and an array of percussion instruments allowed Boulez to expand upon the original, the arrangement of the in total nine players- 3 each for piano, harp and percussion- in space, really adds an extra dimension that takes this concept far beyond early protagonists like Stockhausen.
While the intellectual content of Sur Incises does justify ginz1's description of "etude", to me the impact of this two-part work is truly symphonic. This work takes Webern's ideas on variation and "Klangfarben" (=timbres) and integrates them with themes and elements that trace back through Nono and Messiaen to Debussy. The result is a true feast for the senses and keeps you glued to the speakers for all of it's 37 minutes.
A final word on the recording. Whether in editions of DG, Erato or smaller labels, IRCAM recordings are often technical marvels. This recording is no exception. While their approach to the piano is often more aimed at clarity and dynamics than at warmth, the inclusion of harps, marimbas, bells, triangles etc. really give you the best of all worlds here. The sound stage is EXTREMELY wide and deep and each of the nine players has a rock solid place in it. As such, the information that the spatial transitions of themes and variations from one player to the next provide gets transferred flawlessly to the listening room.
While the other two works on this cd were interesting, they lacked the level of mastery of Sur Incises to me.
Both the level of the composition, their performance and the recording place this cd in the category milestones. While I do hope that DG can seduce Pierre Boulez to record the likes of Mozart's G minor Kv 550, Beethoven's 7th and Bruckner's 3rd, I do hope that he will continue writing masterpieces.