We went with 2 adults, my son (13), my niece (13) and my daughter (10). The recommended age (Lower) is 12 but they allow as young as 10. My daughter was fine, however I'm glad we brought my niece with us, as my daughters paddling skills may have made it harder!
Our guide (Braxton?) was amazing. He knew we were a little worried about my daughter and he guided us great! Was informative about the area and talked a little about himself when we asked too!
My son and niece loved the tour (Lower) and wanted to do another one right then. My daughter enjoyed also, she just wished it was all rapids and no breaks! :) We would definitely do again.