I think this is based on a similar show in Disneyland. It's really good, but if you want the full effect you need to make sure you can hear the narration over the loudspeakers as the 'story' is largely told by Jimminy Cricket. It's a great fireworks show.
We've really lucked-out with the timing of our October trip, what with Dreams, Mickey's Philharmagic and the offical Mission Space opening taking place. I kind of hope we get to see FITS once more though, just for old times sake.