This is a rare, sprawling character piece by the 19th-century American pioneer Anthony Philip Heinrich. It is musically distinctive for its unbridled, idiosyncratic Romanticism that blends European tradition with a unique, early-American adventurous spirit.
The primary challenge is maintaining structural cohesion and expressive phrasing throughout its long, improvisatory-style formal architecture.
Comparable difficulty and character — good candidates for what to learn next.
An Elegiac Impromptu Fantasia is rated Henle level 6 of 9 — advanced repertoire, roughly ABRSM grades 7–8. In the RCM system it corresponds to about level 8.
You should be comfortable at Henle level 6 — meaning you can already play level 5–6 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 An Elegiac Impromptu Fantasia lasts about 8 minutes.
An Elegiac Impromptu Fantasia 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 Barcarolle by Mykola Lysenko, Canon by Sergei Rachmaninoff, Bilder aus Osten by Robert Schumann — see the full similar-pieces list on this page.