Just that basically. My thoughts were it was too young - between the heat, the walking, the activities, the excitement etc. I would be worried its a very expensive way to end up with a cranky kid who didn't enjoy it as much as they would if they were a few years older. I was thinking more like 7/8 would be the youngest I'd consider it.
Would love to hear stories from people who have done it and the pros/cons of taking them young vs later on in primary.