Schubert's Allegro D.154 is a spirited early work that, while not as frequently performed as his later sonatas, showcases his burgeoning melodic genius and dramatic flair.
The challenge lies in balancing the virtuosic runs with expressive phrasing and the use of rubato.
Allegro in E major (D.154) is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 8.
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.
A typical performance of Allegro in E major (D.154) lasts about 4 minutes.
Allegro in E major (D.154) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.