Schubert's "Ave Maria" (Ellens dritter Gesang) is one of the most beloved and iconic settings of the prayer, renowned for its sublime melody and deeply devotional character. Its appeal lies in its profound emotional sincerity and flowing, arpeggiated accompaniment.
Mastering the flowing arpeggios while maintaining a sublime cantabile melody is the primary challenge.
Ave Maria is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 9.
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 Ave Maria lasts about 5 minutes.
Ave Maria is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.