Beyond that, it's well miked and well recorded overall. There's good sound separation here.
This New Yorker profile is a great look at his musical idea-making and more.
Here's another great sample — just one movement, but the third movement, the "Frere Jacques," of the First Symphony. It's got so much suppleness, yet dynamism:
I'm ready to pitch all of my Boulez and assorted other Mahler conductors.