AdEspresso is an app and service provided to Facebook advertisers who're looking to drastically improve their return on investment in Facebook ads. It provides a sizable suite of features to its users, but even using one can improve ROI. This varies, of course: AdEspresso works best when you have an ad campaign in progress that you would like to improve. It is not something, necessarily, to try out or use when you're just starting a Facebook ad campaign. But within those confines, most advertisers will find at least one of its several features useful in moments.