Writing is exhilarating, but reading reviews is not. I've been really devastated by 'good' reviews because they misunderstand the project of the book. It can be strangely galvanising to get a 'bad' one.
In improvising, you've got your scale; you've got the notes that are going to sound good with other notes, the intervals that are going to sound good. But you've also got all the chromatic possibilities, the possibilities of sounding dissident, of being unexpected.