I noticed this the first time we stopped by, though for some reason I noticed the hostesses using them more visibly than the servers. Tablets are becoming more and more common in restaurants, which I think is brilliant. Far more efficient than an apron full of pens and paper or a table map and grease pencils.
If you stop by, do have the brisket quesadillas. (Also, they're opening a second location in Waterloo at Waterloo Town Square on King St. in the late summer/early fall.)
I would definitely love to check it out someday. I'm on the west coast. So unless I'm in the area, I'll have to wait. I for one would love to see the tablets built into the table where one could order for themselves, and then the server just brings you the goodies. You could also have a call button. That way no one bothers you unless you want to be bothered.
As is, no way you could just build the tablet into the tabletop for ordering. The glass would get destroyed really quickly, and moisture would find a way in, too. I suppose you could have the tablet rise out of the tabletop and go back in after you order, but that seems like an unnecessary expense, and just one more thing to break. (And restaurant customers will break EVERYTHING.)
And honestly, having spent 8 years as a server, I can guarantee that far, far more people than you'd think would not be able to figure out the ordering or just not want to use the software, no matter how simple, graphical, or idiot-proof you think it might be. (Plus, there will always be requests, inquiries, substitutions, etc. that won't be covered on the menu that would require someone to come over and answer anyway.)
A call button is more feasible, but if the place was really busy, the server would only be able to come when available, anyway, and not necessarily exactly when you want.