Were you planning on starting fairly early in the morning and going non-stop all day? Perhaps then it would be a bit much to ask him to remain happy that long. Are you going to go back to your hotel during the day for a bit more "down-time" then perhaps you can consider it.
As maci mentioned there are some loud noises. There will be lots of people. When it comes time to exit (after show) it can take over twenty minutes to clear out of the theater and then there is a VERY long line to get back to the resorts (are you staying on property?).
This is a great show but in order to get decent seats, you have to wait in a long line about an hour before the show starts. Then you have to wait until dark/theater full etc. Could you recruit someone to save you seats?
Good luck!
Brenda