Mozart's 'Adagio und Rondo' K.617 is a brilliant and engaging work, originally conceived for the glass harmonica. It features a charmingly lyrical Adagio contrasted with a spirited and technically demanding Rondo, showcasing Mozart's ability to write engaging melodies and vibrant passagework.
The piece demands both expressive lyricism in the Adagio and precise finger dexterity for the rapid Rondo passages.
Adagio und Rondo (K.617) is rated Henle level 6 of 9 — advanced repertoire, roughly ABRSM grades 7–8. In the RCM system it corresponds to about level 8.
You should be comfortable at Henle level 6 — meaning you can already play level 5–6 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 Adagio und Rondo (K.617) lasts about 7 minutes.
Adagio und Rondo (K.617) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.