I don't think this could be mistaken for Haydn or Mozart: it has a kind of rough energy that we will learn to call Beethovenian. The formal scheme is straightforward. The second movement as well has a kind of simplicity to its plan that recalls Haydn. An opening section in Eb major is followed by a middle section in Eb minor. Then the first section returns. The movement ends with a coda, first hinting at G minor, then Ab major, then sliding into Eb major. One interesting touch is the off-beat suddenly loud (subito forte) chords that will become a Beethoven trademark.
The third movement, a scherzo, plays with the rhythmic device of alternating 3x2 with 2x3. This trick, usable in any triple time signature, is ubiquitous in flamenco music, but sounds quite different here. The scherzo, an invention of Haydn as a more energetic replacement for the sedate minuet, reveals that aspect of Classical style that the English musicologist Donald Francis Tovey called 'high comedy'.
Except in the trio, the downbeat is rarely where you think it is. This brings us to the last and most fascinating movement. The movement itself, an Allegretto quasi Allegro is nothing extraordinary, a quick German dance that would not be too out of place in a Viennese ballroom. But Beethoven precedes this with an introduction, which he titles La Malinconia, that no other composer could have written, certainly not at this time. This introduction unfolds an harmonic labyrinth that the rest of the quartet gives no hint of. It is extraordinarily dense piece of music. The Bb of the beginning transforms itself through chromatic movement that never goes where we expect it. When Beethoven arrives at B major in measures 18 to 20, it would be the simplest thing to return to Bb as B major is the Neapolitan. But no. In the second half of this short movement, two new themes appear in a free fugue-like texture that modulates from E minor, to B minor to F# and so on. Beethoven takes us to some very strange places in this movement. And then follows it with a smooth, elegant dance--almost the opposite to the Malinconia. This alternation of opposites, like the alternation of loud and soft chords, will be a technique that Beethoven will pursue to the end of his life.