The game has a special character who, if the player enables the Smartglass app on their phone or tablet, will actually call or text the player’s real-world device with exclusive missions. On the positive side of things, this does add an extra potential level of immersion for some gamers, and as a gimmick, it is unique.
On the other hand, it also means you either have a phone or tablet incorporating Smartglass, or you are going to miss out on this content since it will only be available if you actively allow it to send you calls and texts. This also means either paying for texts and unlimited minutes, or you might actually start finding notable charges on your phone bill as a direct result of your gaming.
If you are one of the people for whom such limitations are not an issue, however, it could be an interesting mechanic if handled well. After all, with the Kinect on, you certainly do not need to be worried about it costing you any more privacy!