This composition by Alexander B. Bulloso functions as an experimental etude, focusing on rhythmic displacement and tonal dissonance. It challenges the performer with irregular groupings and abrupt shifts in musical intensity.
The technical difficulty lies in executing the polyrhythms with consistent dynamic control.
Comparable difficulty and character — good candidates for what to learn next.
11 - 11/9/21 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 11 - 11/9/21 lasts about 3 minutes.
11 - 11/9/21 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 Piano Sonata No. 17 'Tempest', No. 2 by Ludwig van Beethoven, Allegro de concert by Aleksandr Scriabin, 'The King of the Jews' - Incidental Music by Alexander Glazunov — see the full similar-pieces list on this page.