Cramer's sonatas offer a significant body of work in the Classical repertoire, known for their clarity, melodic invention, and pedagogical value. They typically balance lyrical passages with more virtuosic sections.
Develop evenness and control in rapid passages while maintaining expressive melodic lines.
3 Sonatas is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 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.
3 Sonatas is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.