Schubert's D.156 Variations in F major are a delightful example of his early compositional maturity, offering imaginative transformations of a simple theme. The music displays his characteristic melodic inventiveness and harmonic color.
Mastering the rapid shifts in character and dynamics between the variations is a key challenge.
10 Variations in F major (D.156) is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 7.
You should be comfortable at Henle level 5 — meaning you can already play level 4–5 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 10 Variations in F major (D.156) lasts about 15 minutes.
10 Variations in F major (D.156) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.