Rated 4 out of 5 stars
I've been using this add-on for nine months. It is truly indispensable. With jV installed I rarely shell out to gVim via ItsAllText anymore. jV even works with fancy text areas such as those created by the Google Web Toolkit.
The only reason I'm not yet giving it five stars is it doesn't work very well with Google Docs spreadsheets and I have to manually disable it in that context.