Johann Baptist Cramer's Op.43 sonatas are important pedagogical works from the Classical period. They offer clear musical ideas and pianistic challenges designed to cultivate technical skill.
Focus on maintaining evenness in rapid scalar and arpeggiated passages.
3 Piano Sonatas (Op.43) is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7.
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.
A typical performance of 3 Piano Sonatas (Op.43) lasts about 16 minutes.
3 Piano Sonatas (Op.43) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.