Johann Baptist Cramer's Op.23 sonatas are characteristic works of the Classical era, showcasing clear structures and melodic clarity. They are often studied for their pedagogical value in developing solid pianistic technique.
Focus on clean articulation and consistent Alberti bass patterns.
3 Piano Sonatas (Op.23) is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6.
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.
3 Piano Sonatas (Op.23) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.