The ability for us as marketers within our organization -to understand who we are targeting in each country around them so that communication could be made easier at an individual level.- Also it gives you insight into what your competitors products/marketing tactics might look like if they were doing similar things here locally (we have done this now).
It took some time getting used too but once people started using all features there really isn't anything I dislike about Etailsight other then maybe having different templates or design formats available depending where one operates? We use ETI's insights mainly internally however when working internationally its great because most campaigns run across multiple countries giving me complete overviews from my dashboard!