This is a contemporary salon-style ballade written in a neo-Romantic musical language. It features a nostalgic, sweeping melodic line contrasted with a more rhythmic, pulsating accompaniment.
The primary challenge is maintaining a seamless singing tone during the wide-spanning, melancholic melodic arches.
Comparable difficulty and character — good candidates for what to learn next.
Ballad for the unsung heroes 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 Ballad for the unsung heroes lasts about 4 minutes.
Ballad for the unsung heroes 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 Ballade by Henri Rosellen, Ballade by Hugo Wehrle, 'Who Knows?' by Ernest Roland Ball — see the full similar-pieces list on this page.