Kalkbrenner's setting of this popular melody is a classic example of high-Classical variation writing intended for domestic performance. It is distinctive for its straightforward, balanced structure and accessible yet effective keyboard passagework.
Practice the scale passages for evenness to ensure they do not sound mechanical or rushed.
Comparable difficulty and character — good candidates for what to learn next.
12 Variations on 'Freut euch des Lebens' is rated Henle level 3 of 9 — late beginner repertoire, roughly ABRSM grades 4–5. In the RCM system it corresponds to about level 5.
You should be comfortable at Henle level 3 — meaning you can already play level 2–3 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 Variations on 'Freut euch des Lebens' lasts about 5 minutes.
12 Variations on 'Freut euch des Lebens' 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 Alexander's Ragtime Band by Irving Berlin, Waltz in D-flat major, No. 1 by Frédéric Chopin, 12 Variations on 'Ah vous dirai-je, Maman' by Wolfgang Amadeus Mozart — see the full similar-pieces list on this page.