BWV 663 is another magnificent chorale prelude by J.S. Bach, characterized by its intricate counterpoint and emotional depth. It offers a more active and passionate exploration of the hymn tune.
The primary technical hurdle is articulating the more energetic contrapuntal lines with precision while maintaining harmonic clarity.
Allein Gott in der Höh sei Ehr (BWV 663) 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 Allein Gott in der Höh sei Ehr (BWV 663) lasts about 4 minutes.
Allein Gott in der Höh sei Ehr (BWV 663) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.