Si j'étais... Op. 8 is a virtuosic work influenced by the late Romantic etude tradition. It is distinguished by its sweeping arpeggiated figures and emotional intensity typical of 19th-century salon music.
The main technical hurdle is ensuring clean, even execution of the rapid arpeggio figures throughout.
Comparable difficulty and character — good candidates for what to learn next.
"Si j'étais..." (Op.8) is rated Henle level 6 of 9 — advanced repertoire, roughly ABRSM grades 7–8. In the RCM system it corresponds to about level 8.
You should be comfortable at Henle level 6 — meaning you can already play level 5–6 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 "Si j'étais..." (Op.8) lasts about 5 minutes.
"Si j'étais..." (Op.8) 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 16 Waltzes by Johannes Brahms, Albumblatt in Walzerform by Franz Liszt, Ballade by Cécile Chaminade — see the full similar-pieces list on this page.