Good? Bad? Favorites? Hardest?
I listen primarily to no. 24 "Bravura" and no. 45 "Scherzo alla Napolitana," the two hardest (as far as I know). IMO Bravura is both harder and better, being my favorite of the set.
Surely these Etudes are harder than Liszt's and Chopin's. I'd put them right below Godowsky's 53 Studies on Chopin's Etudes and just above Liszt's Douze Grande Etudes. In terms of individual pieces, I'd put both no. 24 and no. 45 as some of the hardest etudes for piano; right up there with Liszt's 1838 Paganini Etude 4b, the 1837 Wilde Jagd, and Godowsky's hardest studies (e.g "Badinage" and the incomplete Study no. 50).
I'm curious to hear what others think about the op. 63 Etudes.
Bravura:
Scherzo alla Napolitana*:
*performed significantly below tempo.