It's definitely cool. We just saw it a few weeks back. It's pretty much as above. Hang around when the march is over, some of the storm troopers stick around and will interact with guests, mostly kids. It's hysterical. Make sure your son gets to do that, he'll love it. Have him wear something Star Wars that day.
They also have some interactive characters in and around Launch Bay. It's fun. There was a thread on here not that long ago about Kylo Ren interacting with people and "scaring" them. It's great.