Franz Schubert's '4 Canzonas' D.688 are early instrumental pieces that showcase his melodic gift and harmonic inventiveness. They often possess a lyrical and song-like character, typical of his style.
The main technical challenge is achieving a seamless legato and expressive shaping of the melodic lines.
4 Canzonas (D.688) is rated Henle level 6 of 9 — advanced repertoire, roughly ABRSM grades 7–8. In the RCM system it corresponds to about level 7.
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 4 Canzonas (D.688) lasts about 16 minutes.
4 Canzonas (D.688) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.