Joseph Gungl was a prolific composer of dance music, and this waltz exemplifies the light, Viennese salon style. It features idiomatic accompaniment patterns and flowing, melodic lines.
Balance the bass accompaniment with the right-hand melody to avoid a heavy sound.
Comparable difficulty and character — good candidates for what to learn next.
Blau-Veilchen (Op.172) is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 6.
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 Blau-Veilchen (Op.172) lasts about 5 minutes.
Blau-Veilchen (Op.172) 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 Brünner-Polka by Joseph Gungl, Broadway Quick Step by Joseph Gungl, Bells across the Meadows (Characteristic Intermezzo)) by Albert William Ketèlbey — see the full similar-pieces list on this page.