Bonheur Chimique is a contemporary work that explores complex sonic textures and dissonant harmony. It stands out for its use of unconventional pedal techniques to create a wash of sound.
The difficulty lies in managing the complex, layered textures to avoid muddiness in the pedaling.
Comparable difficulty and character — good candidates for what to learn next.
Bonheur Chimique is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 8.
You should be comfortable at Henle level 5 — meaning you can already play level 4–5 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 Bonheur Chimique lasts about 5 minutes.
Bonheur Chimique 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 Gymnopédie No. 1 by Erik Satie, La cathédrale engloutie by Claude Debussy, Gnossienne No. 1 by Erik Satie — see the full similar-pieces list on this page.