This fantasy is based on themes from Meyerbeer's opera, composed by the virtuoso Maurice Strakosch. It features typical 19th-century operatic embellishments, including rapid scales and dramatic tremolos.
The technical difficulty centers on executing the rapid octave passages with evenness and power.
Comparable difficulty and character — good candidates for what to learn next.
'Robert le Diable' Fantaisie is rated Henle level 6 of 9 — advanced repertoire, roughly ABRSM grades 7–8. In the RCM system it corresponds to about level 9.
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 'Robert le Diable' Fantaisie lasts about 7 minutes.
'Robert le Diable' Fantaisie 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 Banjo, Capriccio Characterisque by Maurice Strakosch, 'Ch'io mi scordi di te?' by Wolfgang Amadeus Mozart, Piano Sonata No. 8 'Pathétique' by Ludwig van Beethoven — see the full similar-pieces list on this page.