A work by the prolific contemporary of Haydn and Mozart that adheres to the clean stylistic norms of the Viennese Classical period. It is distinguished by its graceful melody and balanced phrasing.
The main challenge is maintaining a steady, singing tone while executing precise Classical-style ornaments.
Comparable difficulty and character — good candidates for what to learn next.
Andante sostenuto in A major is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 5.
You should be comfortable at Henle level 4 — meaning you can already play level 3–4 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of Andante sostenuto in A major lasts about 3 minutes.
Andante sostenuto in A major is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include Allegretto in A major by Johann Baptist Vanhal, Andante sostenuto in C minor by Johann Baptist Vanhal, Andante by Wolfgang Amadeus Mozart — see the full similar-pieces list on this page.