This sonata is a relatively simple work, less refined than most other piano sonatas. Surprisingly, there are no dynamic indications in the autograph and first edition. It is considered to be the lighter of the two ‘light sonatas’ and also the simplest of all Beethoven's piano sonatas
The first movement involves two themes, starting with a stately theme based heavily on a G major triad and moving on to a more playful and lively second theme in D major, also based on the triad of D major. Both themes undergo only minimal development in the keys of D minor, A minor, and E minor before the recapitulation with the themes presented in the tonic G major and its subdominant C major, making for a simplified sonata form. The work features, for the pianist, extreme triplet technique in both hands and the balance between the hands is most critical.
The second movement of the Piano Sonata No. 20 shares a melodic theme with the Minuet of the Op. 20 Septet. Because the Septet was the later piece (1799–1800), Beethoven's suppression of the sonata and reuse of one of its themes suggests that he perhaps planned to scrap the piano work altogether. But the composer was known to recycle melodies, in some instances several times (for example, the Eroica Variations). This movement is cast in the form of a rondo, with the main rondo theme being, essentially, a minuet; the minuet features a charming melody that, along with its accompanying material, is repeated several times, varying somewhat in appearance, but remaining simple and unsophisticated.