Tchaikovsky's '12 Pieces' Op. 40 is a delightful collection of miniatures, each offering a distinct mood and character. They are notable for their melodic charm and evocative pianistic writing.
Emphasis on expressive dynamics and achieving a rich, resonant sound with the pedal.
12 Pieces (Op.40) is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 7.
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 12 Pieces (Op.40) lasts about 20 minutes.
12 Pieces (Op.40) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.