Notturno is simply "nocturne" with an Italian aroma. Bella Vita, eh!
Many concert works in the standard repertoire are placed in keys with five flats of sharps or more, as this piece illustrates. The reason for this is not mere "virtuosity" or even intellectual hubris. The black-keys afford an access to many kinds of gestures that alternate between the black and white keys, for two hands, in a way that placement in C, F or G simply do not provide. Having the hands in and up over the black keys affords, as in this case, an easy alternation between an upper and lower hand gesture, without having to be in the same keyplane.
Why are the black keys easier for this, you might ask, since they are ALSO in a uniform plane? The white keys have no diatonic gaps, but the black keys, forming a pentatonic scale with two gaps, does indeed afford just such a place to place these sorts of piano-drumming gestures. The main distinguishing feature of our setting here is the elimination of this top melody tone, which dies so fast,and yet in standard editions gets smeared across the top of many lines like excess frosting that has already been eaten.
Our edition shows when each gesture begins, and does NOT emphasize how long these drawn-out single tones last, over the accompaniment. Spellings are better, and pedaling is included throughout, rather than left to laissez-faire. 10ths are often used here, and are shown are arpeggiandi throughout.
The MIDI file playback here does not really convey how much rubato can be applied to this piece, in a most musical and entertaining way, as the composer intended. MBB.