Op. 133 is an evocative, modern work that utilizes complex textures to convey a pacifist message. Its distinctiveness comes from the deliberate juxtaposition of dissonant, layered clusters with quiet, minimalist passages.
Mastering the control of voicing within dense, layered textures is the primary challenge.
Comparable difficulty and character — good candidates for what to learn next.
(Ver)suche Frieden... (Op.133) 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 (Ver)suche Frieden... (Op.133) lasts about 5 minutes.
(Ver)suche Frieden... (Op.133) 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 (Ver)suche Frieden... by C. René Hirschfeld, La cathédrale engloutie by Claude Debussy, Canope by Claude Debussy — see the full similar-pieces list on this page.