My kids both did it. They went tandem with my husband and I. It was glorious and we all loved it. Would do it again in a heartbeat.... There were some younger kids that went, as well, and they enjoyed it, too. It was peaceful and secure feeling. The take off and landing was never scary. The toe-dip was warm and fun, as well.
The operators will not let your young one go alone. I think that YOU should go with her!!! I believe that the child's reaction may depend on personality. If your daughter is generally very cautious, this might not be the thing for her. If she is adventurous and you can bring yourself to go, it is an amazing experience. GO FOR IT!!!! (We greatly preferred the parasail over the salt water-in-the-eyes, bouncy, banana boat that felt like you were going to fall off any minute!)