Chances are he won't follow the storyline, but it is **LOUD**. Really loud. I've seen four and five year olds freak out from the volume... the fire is kinda scary, too.
See how he reacts to big fireworks this summer. Sit near an end and be ready to roll.
By the way, speaking of strollers, you cannot take yours into the seating area. I'd leave it behind for this trip to MGM. As you're exiting the theater they have complimentary strollers for the walk out.
good luck,
Ronda