Józef Nowakowski was a Polish pianist and composer influenced by his contemporary, Chopin. This piece captures the sentimental and dramatic flavor of the mid-19th century Polish piano school.
The performer must balance the delicate ornamentation against the underlying rhythmic pulse.
Comparable difficulty and character — good candidates for what to learn next.
Ballade No.2 (Op.64) is rated Henle level 6 of 9 — advanced repertoire, roughly ABRSM grades 7–8.
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.
Ballade No.2 (Op.64) 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 No.1 by Józef Nowakowski, Ballade by Józef Nowakowski, Liebestraum No. 3 in A-flat major by Franz Liszt — see the full similar-pieces list on this page.