Friedrich Kiel was a master of formal discipline, and his Bolero reflects a synthesis of classical structure with characterful, romantic gestures. It is noted for its clean textures and subtle interplay of voices.
Clear articulation and independence between the contrapuntal lines are essential for success.
Comparable difficulty and character — good candidates for what to learn next.
Bolero 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.
A typical performance of Bolero lasts about 6 minutes.
Bolero 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 Bergamasca by Girolamo Frescobaldi, Keyboard Sonata in E-flat major by Joseph Haydn, Caprice et Sonate by Johann Wilhelm Hässler — see the full similar-pieces list on this page.