This early Rachmaninoff work demonstrates his innate talent for long, arching melodies layered over a contrapuntal bass. It is musically distinctive for its Russian emotional depth compressed into a traditional formal structure.
The challenge is balancing the lyrical top voice against the moving, independent inner lines.
Comparable difficulty and character — good candidates for what to learn next.
Canon in E minor 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 Canon in E minor lasts about 3 minutes.
Canon in E 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 Barcarolle by Anton Stepanovich Arensky, Albumblatt in A minor by Johannes Brahms, Ballade by Amy Marcy Beach — see the full similar-pieces list on this page.