A simple melodic composition intended for ease of listening and playing. It utilizes common harmonic progressions that evoke a feeling of nostalgia.
Controlling the touch to create a smooth, vocal-like legato is the main technical requirement.
Comparable difficulty and character — good candidates for what to learn next.
'Twas in the Glorious Month of May is rated Henle level 2 of 9 — beginner repertoire, roughly ABRSM grades 2–3. In the RCM system it corresponds to about level 3.
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 in the Glorious Month of May lasts about 3 minutes.
'Twas in the Glorious Month of May 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 Believe Me, If All those Endearing Young Charms by Irish Folk Music, Blue Moon by Lee S. Roberts, Arroz con leche by Wannes Vanderhoeven — see the full similar-pieces list on this page.