Charles Delioux was a skilled French virtuoso; this piece reflects his ability to combine technical decoration with deep, melancholic sentiment. It is a prime example of the elevated salon repertoire that demands emotional maturity.
The primary challenge is balancing the decorative passage work with the underlying expressive melody.
Comparable difficulty and character — good candidates for what to learn next.
Bonheur passé (Op.70) is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 6.
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 passé (Op.70) lasts about 4 minutes.
Bonheur passé (Op.70) 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 Nocturne in C-sharp minor by Frédéric Chopin, Prelude in E minor, No. 4 by Frédéric Chopin, Albumblad by Edvard Grieg — see the full similar-pieces list on this page.