BWV 662a is a variation or related version of Bach's serene chorale prelude, BWV 662. It shares the same profound expressiveness, intricate counterpoint, and focus on devotional beauty.
Maintaining a seamless legato and achieving a warm, resonant sound in all voices is paramount.
Allein Gott in der Höh sei Ehr (BWV 662a) is rated Henle level 3 of 9 — late beginner repertoire, roughly ABRSM grades 4–5. In the RCM system it corresponds to about level 7.
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 Allein Gott in der Höh sei Ehr (BWV 662a) lasts about 4 minutes.
Allein Gott in der Höh sei Ehr (BWV 662a) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.