We went on this trip back in June. My sister is in the process of writing a report about it here. While we don't have children, there were quite a few children on our trip. I believe the boys on our trip were around 8. The only spot I would "warn" you about is the zip lining, but it depends on your child's height. I don't know how tall the kids were but the youngest ones who were shorter had a bit of trouble at times. I don't think it caused too many problems, but I would just make sure an adult is in front of and behind her, that way someone can help her prepare to go across, and one can be on the other side to help her get onto the podium or lower herself. Other than that she would be fine to keep up with everything! It was a fantastic trip!
Not sure if it is still the same, but when we went ~5 years ago, you needed to be 8 years old to go on the main zipline course. For those younger than 8, they had a small zipline that the kids finished in about 15 minutes and had to wait. Our son was 2 weeks shy of 8, so we had to really cajole the owner to let him on the main course. As Kanadar says, we had one adult in front, and one behind. But he had a blast on the zipline course.