This is a neo-Baroque construction featuring a somber chorale followed by a rigorous, four-part fugue in C minor. It is notable for its structural complexity and dense, intellectual layout.
At Henle 7 this is a late-advanced work — the technical demands are serious and sustained. The main demands: independent voices that must each sing on their own line; fine finger independence within the hand; and chord voicing — bringing out one note inside a handful of others.
Beyond that, expect several simultaneous layers, each needing its own dynamic level.
The complex subject and countersubject require advanced finger independence to maintain clarity in all parts.
Comparable difficulty and character — good candidates for what to learn next.
A level or two down with the same spirit — ideal if this piece is still out of reach.
Where this piece's skills lead: slightly harder works making similar technical demands.
Chorale and Fugue in C minor is rated Henle level 7 of 9 — late advanced repertoire, roughly ABRSM grade 8 and above. In the RCM system it corresponds to about level 9.
You should be comfortable at Henle level 7 — meaning you can already play level 6–7 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 Chorale and Fugue in C minor lasts about 6 minutes.
Chorale and Fugue in C minor 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 Chorale and Fugue in Cm by Leslie Joseph Deutsch, Chromatic Fantasia and Fugue by Johann Sebastian Bach, Variations and Fugue on a Theme by Handel by Johannes Brahms — see the full similar-pieces list on this page.