Part of the 'Goyescas' suite, this piece reflects Granados's fascination with the art of Goya and the traditions of 18th-century Spain. It is highly characteristic for its florid, bird-like ornamentation and its deeply expressive, improvisatory melodic lines.
Mastering the subtle, nuanced ornamentation and creating a delicate, bird-like tone quality requires significant refinement of touch.
Comparable difficulty and character — good candidates for what to learn next.
Quejas, o la maja y el ruiseñor is rated Henle level 6 of 9 — advanced repertoire, roughly ABRSM grades 7–8. In the RCM system it corresponds to about level 9.
You should be comfortable at Henle level 6 — meaning you can already play level 5–6 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 Quejas, o la maja y el ruiseñor lasts about 5 minutes.
Quejas, o la maja y el ruiseñor 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 Liebestraum No. 3 in A-flat major by Franz Liszt, Pavane pour une infante défunte by Maurice Ravel, Bethena by Scott Joplin — see the full similar-pieces list on this page.