Clemens J. Setz at Music and Literature:
They are highly virtuosic pieces, which, I assume, must not be played slowly, because then you would hear and see nothing, just as when you walk too slowly past a fence, you perceive the flashes of life from behind it not as a cohesive picture, but rather only as disparate snapshots. The first etude, “In C,” is indeed, as the title reveals, built around this fundamental note. It conveys a mysteriously contemplative and at the same time very harmonious impression. In several slow breaths, flickering structures are built up repeatedly to towering heights. In the second part, nested rhythms become so dense that they generate the gingerbread men feeling. The etude is heading for a climax, but then no explosive outburst occurs; instead, individual melodic lines break free in a high register and simply waft away.
more here.