Johann Wilhelm Hässler was a transitional figure between the Baroque and Classical styles. His hybrid 'Caprice et Sonate' forms blend contrapuntal rigor with developing classical formal structures.
The player must balance the clarity of the melodic line against the structural requirement of the Alberti-bass accompaniment.
Comparable difficulty and character — good candidates for what to learn next.
Caprice et Sonate (Op.2) 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 Caprice et Sonate (Op.2) lasts about 7 minutes.
Caprice et Sonate (Op.2) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include Caprice et Sonate by Johann Wilhelm Hässler, Keyboard Sonata in E-flat major by Joseph Haydn, Capriccio di obligo di cantare la quinta parte, F 4.11 by Girolamo Frescobaldi — see the full similar-pieces list on this page.