We have not used them but have 2 experiences with them, both very positive.
A coworker took her 2 kids (5 yr old and 11 yr old) with her and husband on one. They had a blast. Older daughter got to get certified, made lots of fiends her age. Younger one got to snorkel and play with dolphins. They did the Sea Camp at Anthony's Key Roatan. Both kids loved it and wanted to stay... cried all the way home on plane.
My husband and I went to Bonaire back in 2007, stayed at Buddy Dive, at the same time there was a Sea Camp there. We thought it would be a bother, but it wasn't. The kids were in groups by age, always busy with instructors during mornings, then free in afternoons to be with families. Looked like a blast and wish we had done something with our daughter when she was young.
All in all, I would say from my viewpoint it is a fantastic program.