We occasionally eat at Applebees and have seen these tablets at each table. I've watched closely and never seen anyone purchase food using them. We've never ordered from them either.
Buffalo Wild Wings uses tablets for a trivia game and has for some time. It appears to be rugged enough and to attract and hold players. The Applebees approach seems well thought-out and I am betting will prove a keeper.
Someone knocking over a glass of water on the table could fry the thing too. They could just do an App so that people could order via their own phone. Chipotle does that.