This is a parlor-style waltz reflecting the sentimental popular song tradition of the early 20th century. It features a straightforward melodic structure supported by a traditional harmonic accompaniment.
The main challenge is achieving a graceful and consistent waltz rhythm in the left hand.
Comparable difficulty and character — good candidates for what to learn next.
'Twas A Kiss In The Moonlight is rated Henle level 2 of 9 — beginner repertoire, roughly ABRSM grades 2–3. In the RCM system it corresponds to about level 2.
You should be comfortable at Henle level 2 — meaning you can already play level 1–2 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 'Twas A Kiss In The Moonlight lasts about 3 minutes.
'Twas A Kiss In The Moonlight 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 Für Elise by Ludwig van Beethoven, 'O marenariello by Salvatore Gambardella, Butterfly Lovers by Shuwen Zhang — see the full similar-pieces list on this page.