The widget is in the old four by one block style that we've seen since the N97. However, it takes advantage of the size to show you your cellular data usage, WiFi usage, and your mobile data limit. The application doesn't display any data, but there are menu options to change your mobile data limit and to reset your counters.
Given that the latest set of Symbian widgets provides the most important half of this app's functionality, you'd have to have a good reason to need to track your WiFi usage too. If that describes you, the go pick it up for £1 at the Nokia Store.