I love this kind of stuff. As an amateur magician I find this app very neat. Pull it out anywhere; it is so easy to perform one on one.
I have only one suggestion. Add a cool opening screen. Maybe something with all five of the symbols on it so that the spectator will see all the symbols at once, giving him or her a choice. I would have easily paid 99 cents for this app. Personally, I feel that any app that is worth having is worth paying something for, if only to compensate for the hard work and creativity. There is some very cool stuff in the Apps store.