You can password protect the entire iPad, which if you are afraid of someone grabbing it would be smarter than just protecting one app.
And since they can simply turn the iPad off until they are ready to restore it, there is no way to prevent a savvy thief from getting around this kind of app. You'd have to be pretty lucky to catch the in the few seconds a well co-ordinated restore would take.
My iPhone and iPad find each other quite well. Even the iPad 2 worked fine, as long as it was connected to my network.