Customer mode:: order =before= you get to the restaurant, book a table, pre-assigned seating, bill split, rate your food, rate your waiter, etc.
Waiter mode:: When a customer doesn't have their own smartphone/ipad. Plug in with the 'square' for payments.
Kitchen mode:: Customer is 5 minutes away (gps), start cooking! (order added to queue). Just stepped in (bluetooth/wifi?discovery), queue the drinks, ready to plate!
Restaurant mode::seating arrangements, waiter assignments, VIP customer tracking (CRM for restaurant customers! we can track them now.), stats, etc.
Biggest business plan benefit - Instantly scalable, global immediately (it's an app!), lower hardware costs, tie in to upsell restaurants on services, etc etc etc.
ps. I'ld love to have something like that on my phone. And yes, opentable should have really done something like this years ago.