Pierre Boulez has had several phases, and later in life he seems to have been willing to make more compromises with the audience, and to take them into account. I'll go ahead and say it -- he became more "accessible" later on.
Well, the compositions on this two-CD set are from his early, non-accessible period. At least they have their origins there. Boulez revised the works later on, and I'm not sure exactly what changed, for example, between the 1948 and the 1965 versions of "Le Soleil des Eaux", one of the compositions featured here.
I recently read a quote from Boulez's early years, something along the lines of "I don't care how a composition sounds, I care how it is made." Well, as a listener I don't really care how it's made, I care how it sounds. Mr Boulez and I have a fundamental conflict of interest in this respect, it seems.
Listening to CD 1, "Pli selon Pli", I was thinking this is a two-star recording, but I also realized that this is more about me than the performance. Boulez conducted this set with BBC Orchestra players, and the musicians and singer do a fine job, I'm sure. But I just didn't care for the music. Call me shallow and bourgeois, but I need at least a little bit of accessibility. There were some marimba flurries in the piece that I enjoyed, but that's just because I like the marimba.
I put in CD 2 with some trepidation after the first disc, but this actually turned out to be a four-star experience. The compositional model seems similar, but the pieces on the second disc are for full orchestra and feature vocal duets and choruses rather than a single soprano. People singing together mean that there are things resembling harmonies, and instruments playing together mean things resembling chords. Just this much of an acknowledgment by Mr Boulez makes a world of difference. This is still not my favorite music, but the second disc was much more to my liking.
If you love music from the Darmstadt School, I salute you. You'll probably really enjoy these CDs. Those with more pedestrian tastes, such as myself, should probably just jump over the 1950s and 1960s and head straight to things by composers like John Adams and Arvo Pärt. Or even later Boulez. These recordings, however, reflect an almost militant intellectual attitude that seems to have been more about theories and ideas than music.