Due to their structural and thematic links, some envisioned the four Impromptus as parts of a multi-movement sonata, a conjecture which is subject of debate among musicologists and scholars.

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

[2] 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".

This piece has the structure of a sonata exposition but develops into an expressive dialogue between treble and bass with an arpeggiated accompaniment in the middle register.

Alfred Einstein has mentioned another similar theme by Beethoven – in the third movement of the Piano Trio, Op.

The fourth Impromptu (Allegro scherzando) displays Schubert's rhythmic vitality and unpredictable accentuation.

Its contrasting middle section reaches a climax in scale passages for both hands, culminating in a swift, four-octave descent in A major across the entire keyboard.

[6] The work is the most technically demanding of the Impromptus, employing a wide variety of keyboard writing, including scale runs (at times in unison), arpeggios, broken chords, quick passages in thirds, and trills.

It is speculated that Schubert himself may have regarded the four Impromptus as a multi-movement sonata, due to their structural and thematic connections, notably by Robert Schumann and Alfred Einstein, who claim that Schubert called them Impromptus and allowed them to be individually published to enhance their sales potential.

[7] However, this claim has been disputed by contemporary musicologists such as Charles Fisk, who established important differences between the set of Impromptus and Schubert's acknowledged multi-movement works.

[10] The Impromptus have since 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.