Also, same day, it can recalculate what you'd like to do on the fly, in just a few sec. If you are not familiar withe the layout of the parks, I highly recommend using it to help build an itinerary, and a walking path. It does those thing for you, and also allows you to customize using your own common sense. The computer cannot use common sense, but it will give you a fantastic starting point to build an itinerary for what you tell it you want to do. For what it is, it's dirt cheap.
They also have a forum just like this one, for questions.