Originally scored for jazz band and piano, the solo piano version captures the iconic synthesis of classical symphonic structure and American jazz idioms. It is famous for its blue notes, syncopated rhythms, and the virtuosic opening clarinet glissando transcribed for piano.
Maintaining a fluid, jazzy rhythmic swing while executing technically demanding chromatic runs is the fundamental hurdle.
Comparable difficulty and character — good candidates for what to learn next.
Rhapsody in Blue (Solo Piano) is rated Henle level 8 of 9 — concert repertoire, roughly diploma level. In the RCM system it corresponds to about level 10.
You should be comfortable at Henle level 8 — meaning you can already play level 7–8 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 Rhapsody in Blue (Solo Piano) lasts about 16 minutes.
Rhapsody in Blue (Solo Piano) 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 'I Got Rhythm' Variations by George Gershwin, Hungarian Rhapsody No. 2 in C-sharp minor by Franz Liszt, Rondo a capriccio in G major by Ludwig van Beethoven — see the full similar-pieces list on this page.