The WiiPad will be used to display the location of each of the fugitives you're hunting down, just as the touchscreen does on the 3DS version. "When roaming without a TV," WayForward creative director Matt Bozon told Nintendo Power, "a smaller onscreen compass points the way. While this is admittedly not a groundbreaking use of the second screen, it does give the player a few very handy options."
Here it is: the very first 3DS to Wii U remake. We expect to see plenty of these in the future.