Cramer's Op. 4 sonatas are valuable pedagogical works from the Classical era, focusing on clear melodic writing and idiomatic piano technique. They are approachable for students transitioning to more complex repertoire.
Emphasis on clear articulation and control of dynamics within a singing melodic line.
3 Sonatas (Op. 4) 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 3 Sonatas (Op. 4) lasts about 12 minutes.
3 Sonatas (Op. 4) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.