Hummel's music had a lasting effect on his contemporaries. Chopin had two of Hummel's piano concertos in his repertoire, and used them as models for his own piano concertos. Schumann was also influenced by Hummel's second piano concerto. It was the first concerto Schumann studied with his teacher Friedrich Wieck (father of the piano virtuoso and future wife of Schumann, Clara). Schumann used the concerto as a model for his own Piano Concerto in A Minor.
There's not a better way to illustrate Hummel's shift in style of composition than to compare his early attempts at concerto writing with his 2nd in A minor. The Piano Concertino in G, written in 1799 (a transcription of an earlier concerto for mandolin), is generally reminiscent of Mozart's concertos in style and content. The 2nd concerto is more dramatic, has a form more like Beethoven with a more complex part for orchestra. The piano writing for the second concerto is strictly for the virtuoso, with brilliant runs, trills and passages in thirds for both hands. The 2nd Piano concert is in the traditional three movements:
I. Allegro moderato - The orchestral introduction is Beethoven-like in length, and Hummel shows his mastery of orchestral writing throughout. The piano enters and dazzles with piano writing that shows how great a virtuoso Hummel was, as he premiered this concerto in Vienna shortly after its composition in 1816.
II. Larghetto - A short movement, the forerunner of the great slow movements to come in the Chopin concertos. The piano plays a sweet, tastefully decorated nocturne-like melody while the orchestra gently accompanies.
III. Rondo: Allegro moderato - The piano is the star of the finale, with glittering finger work the increases in complexity as melodies are tossed about between orchestra and piano until the work closes with a rousing flourish.
It is quite ironic that a composer such as Hummel, a harbinger of the Romantic movement that was so influential for so many composers, was for many years subject to gross neglect. At the end of his life he was considered somewhat old-fashioned by the leaders of the "New Music". Such is the fate of some who have led the way, only to be bypassed by the rapid change in taste and convention. For whatever the reasons, Hummel's music is now beginning to be heard more often, at least in recordings. It deserves to be heard, if nothing else as a break from the 'warhorses' of the repertoire. The relative handful of concertos that are played most often most assuredly deserve their place in the repertoire, but music such as Hummel's can give them a needed rest on occasion.