The novel is a painting. The short story, a sketch. Flash fiction is a photograph, and, as we know, worth a thousand words.
Personally, I prefer a word count between 200 and 500. I like flash fiction that plays with form, that turns the reading into a game. In my own work I often seek to add further limits to the text, such as in my Fugues, where the three parts, subject, development and recapitulation, serve to introduce, explore and resolve the theme or story.
Writing flash fiction is a perfect compliment to the writing of novels. The liberty of style and content, economy of words, the immediacy of the reader’s reaction, all contribute to the pleasure of producing flash fiction.