G.♣.
I don't know anything about this organization.
If you are concerned about your child's reading skills, I would discuss this with his/her teacher and come up with a list of things to work on this spring and possibly a list of things to work on over the summer.
If your child is significantly behind, then I would discuss the possibility of summer school or summer enrichment or some other program in your area.
The summer reading programs I've heard about market themselves as programs to help your child progress faster than his/her peers. I'm not convinced that's in my child's best interest. It's not that I don't want my child to be a good reader. I do highly value education. I'm just not sure it's in his best interest to be ahead of his peers. I think he should be learning WITH his peers.