Johann Baptist Cramer's sonatas are esteemed for their melodic inventiveness and well-crafted piano writing, typical of the late Classical period. They are often appreciated for their clarity and lyrical qualities.
Requires careful attention to legato phrasing and delicate articulation, particularly in the melodic lines.
3 Piano Sonatas (Op.34) is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 7.
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.
3 Piano Sonatas (Op.34) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.