The third Impromptu is a flowing and meditative piece in G♭ major, characterized by long melodic lines and unbroken triadic accompaniment.

The fourth and final Impromptu, in A♭ major, starts in A♭ minor and is characterized by cascading arpeggios and a chordal response.

[2] The Impromptus were part of the broader Romantic trend of composing short, self-contained piano pieces, a genre popularized in the 1820s.

[2] However, other composers such as Johann Baptist Cramer, Carl Czerny, Heinrich Marschner, Ignaz Moscheles and Franz Liszt also wrote Impromptus published around this time, though Schubert's clearly structured Impromptus largely do not conform to the improvisational traits implied by the literary term "impromptu".

[3] In Schubert's lifetime, only the first two pieces appeared in print, and it remains unclear why the latter two were not published until long after his death.

[3] The first Impromptu (Allegro molto moderato), written in C minor, is a distinctive mixture of sonata, variation, and through-composed elements.

It starts boldly with dominant octaves serving as the background to a muted funeral march contrasted with an imitative, sensuously Italianate closing theme.

Later, a new pattern with straight (non-triplet) semiquavers is used as accompaniment, modulating to G minor and then an off-beat version asserts itself in quavers.

Set in E♭ major, the second Impromptu (Allegro) is a swift moto perpetuo with a ternary design, a common structure among the impromptus.

This section is based on a figure alternating a widely spaced bare octave and an offbeat accented triplet.

There is little interruption in the fluttering harp-like broken triad accompaniment, creating a tense contrast with the spacious and languid melody—an anticipation of Felix Mendelssohn's Songs Without Words.

With no repeats, the melody develops into a shadowy and frequently modulating middle section before returning to its relaxed flow.

The Impromptus have become a staple of the piano repertoire, praised for their lyrical beauty, complex structure, and expressive depth.

They are emblematic of Schubert's mature style, characterized by a combination of directness and intimacy of expression, poetic sensitivity, and structural control and grandeur.