I haven't been to the Kissimmee castle, but the show is the same in all locations. It's good and worth seeing if you've never done it before. A 7 year old would probably love it.
If however, there's another location closer to you I would recommend doing that instead of spending your Orlando vacation time here. They also have shows in Dallas, Buena Park, Baltimore, Atlanta, Lyndhurst, Myrtle Beach, Chicago, Scottsdale [opening 2019] and Toronto.