I downloaded Geo synth today. There's nothing automatic about it... its the same as any other MIDI controller, except that the interface is a smooth piece of glass that allows sliding from note to note (or not)
Like any other instrument, you have to learn where the notes are, then be able to trigger them on beat and without triggering the wrong note. In other words, its a whole new instrument, and in order to use it, you have to learn how to play it. I first thought it would be a toy, but it makes sounds that I would definitely use in a song I wanted other musicians to hear.
All in all, I love it. Best $9.99 I ever spent.