Ernesto Meumann's Op. 14 is a weightier, more harmonically complex work than those of the early Romantic period. Its 'serioso' marking defines a piece driven by gravity and structural integrity rather than virtuosic showmanship.
The main challenge is maintaining a consistent, intense emotional through-line while managing the varied chordal textures.
Comparable difficulty and character — good candidates for what to learn next.
Allegro serioso (Op.14) is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 7.
You should be comfortable at Henle level 5 — meaning you can already play level 4–5 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
Allegro serioso (Op.14) 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 Basso Ostinato, VL 267 by Mikalojus Konstantinas Čiurlionis, Capriccio cromatico con ligature al contrario, F 4.08 by Girolamo Frescobaldi, Allegro in A major by Max Reger — see the full similar-pieces list on this page.