Just Géraldy’s waltz is a quintessential example of light French piano literature from the turn of the century. It is known for its clear, transparent texture and charming melodic inventiveness.
Focus on maintaining a crisp, light articulation that captures the character of a salon dance.
Comparable difficulty and character — good candidates for what to learn next.
Au bal is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 5.
You should be comfortable at Henle level 4 — meaning you can already play level 3–4 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 Au bal lasts about 3 minutes.
Au bal 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 The Entertainer by Scott Joplin, 12 Variations on "Ah vous dirais-je, Maman" by Wolfgang Amadeus Mozart, Piano Sonata No. 11 in A major by Wolfgang Amadeus Mozart — see the full similar-pieces list on this page.