For most of us, our only experience with Muzio Clementi lies solely in the sonatinas that we learned as piano students. Most of have probably also heard about the great piano competition between Clementi and Mozart, which was declared a draw. Mozart was full of vitriol about the decision while Clementi continued to admire Mozart and in fact was a publisher of Mozart's piano music in England.
Clementi was a very accomplished pianist and composer as well as a piano manufacturer, piano retailer, and music publisher. His was one of the early horizontal industries -- he built the pianos, he sold the pianos, and he published the software (sheet music) so that people had plenty of music to play on his pianos.
Unfortunately, he gets little space in the music history books, I suspect because he primarily wrote for the piano with very little music on any other genre.
Here is a link to his biography on Wikipedia: Clementi Biography
It appears that he was a strong influence on Beethoven. I have read where Beethoven advised Carl Czerny concerning Beethoven's nephew Karl's piano instruction, that Czerny should focus on Clementi piano sonatas over those of Haydn and Mozart.
The above piano sonata -- Op. 34, No. 2 (1793) -- may well have been an influence on Beethoven's "Sonata Pathétique" (Op. 13) from 1798. The Clementi sonata begins with a slow introduction with extensive dotted 8th - 16th combinations. It gives me the impression of a funeral march. Unlike the Beethoven, this intro is in a kind of grotesque fugue, each entry of the subject/answer uses a larger descending skip -- (1) descending 5th, (2) descending augmented 5th, (3) descending 6th. This introduction is later reprised as in C major in a style that reminds me of a tavern song in an opera.
There is some very remarkable music in this sonata and if you like Beethoven's sonatas, I believe that you will immensely enjoy this one.
Though it is said that Clementi admired Mozart, he could have his moments of vitriol against Mozart. This sonata was written in 1781, about a year before his famous competition with Mozart. After Mozart wrote "Magic Flute" in 1791, Clementi included a forenote on his reprints of this sonata stating that this had been written 10 years before Mozart's opera. Listen to the above recording and you will understand why. One can also ask "Did Clementi perform this sonata at the competition?"
I am in the process of searching for a good biography of Clementi. He has often been denigrated for his alleged penury and his alleged mistreatment of John Field, both items that I only find mentioned in Ludwig Spohr's "The Musical Journeys" (I think -- I can't find an online copy, though I could have sworn that I had previously downloaded it). I suspect that there is more to the story.