If Chopin did hate this "impromptu" so much, why did he carefully revised it in 1839??
The newer version in his own handwritting bears significant changes in harmonies and counterpoints writting and contains very clear expression marks almost everywhere.
I would like everyone who are working on this piece to have a research on this music in it's 1839 version. Available on wiener urtext edition and chopin national edition edited by Jan Ekier (not so reliable but a foremost musicologist anyway)
.... more about this impropmtu, it was the first improptu written by chopin but had never been published during his lifetime, therefore bare the "no.4" as the title. The term "Fantaisie-impromptu" is not by chopin but has a complicate story. few friends of chopin copied the manuscipt of this "impromptu"by chopin and some has put the name "fantaisie" on it. This fantaisie became quite popular, that later publisher put the combination title as Fantaisie-Impromptu... in Chopin's new 1839 version the title is just "Impromptu"