This is one of Franz Liszt's famous transcriptions of Schubert's Lieder. It transforms the original vocal lines into a rich, piano-based textures that utilize the instrument's full resonance.
The main difficulty is achieving a perfectly balanced cantabile melody over widely spaced chordal accompaniment.
Comparable difficulty and character — good candidates for what to learn next.
Ave Maria after Schubert S558 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 Ave Maria after Schubert S558 lasts about 4 minutes.
Ave Maria after Schubert S558 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 Ave Maria (Die Glocken von Rom) by Franz Liszt, Ave Maria (The Bells of Rome) by Franz Liszt, Ave Maria d'Arcadelt by Franz Liszt — see the full similar-pieces list on this page.