As for the app itself, cool! I'm glad somebody had the audacity to ship something as outrageous as this. I don't think it will get much of a following, but I suppose if you really don't care about your phone or you're really confident in catching this could be a cool, reckless waste of 10 minutes.
EDIT: For clarification, I don't really side with or against Apple in general on things, so this isn't meant to be a "Apple's always a walled garden, BAH" post, etc...I just really feel any company should let users feel free to destroy hardware. But I understand that might not be the best philosophy to run a multinational company.
EDIT2: Just thought of a way to game this after reading another comment - slap on a Lifeproof case, go in a big pool shallow enough to stand, throw it really high. Eliminates the need to catch it (within...reason...).