This is a virtuosic piano transcription of themes from Donizetti's famous opera Anna Bolena. It follows the 19th-century salon tradition of creating brilliant fantasies to showcase operatic melodies through technical embellishments.
The primary challenge is maintaining an operatic vocal quality in the right hand while executing rapid, delicate passagework.
Comparable difficulty and character — good candidates for what to learn next.
'Anna Bolena' fantaisie (Op.204) 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 'Anna Bolena' fantaisie (Op.204) lasts about 8 minutes.
'Anna Bolena' fantaisie (Op.204) 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 Belfagor by Ottorino Respighi, Allegro de Concert by Alexander Scriabin, Boabdil by Moritz Moszkowski — see the full similar-pieces list on this page.