I bought three of these balls: one for my son (aged 11), one for my nephew (aged 14 and about 6ft tall) and one for my dog. The kids were very enthusiastic initially but it didn't last, although that could have been something to do with the temperature of the sea, so I don't want to be too mean here. Our problem was getting the balls to do anything really different from any other ball. I am used to throwing an ordinary dog ball in the sea for the dog, and often as not it skims over the water a little way - this ball does the same, but skims a bit further, though not a lot. Sad to say the dog (German Shepherd) prefers to chase skimmed stones as these skim further and faster, at least in my hands, and the kids have lost interest completely.
I think these balls would be most effective in a swimming pool if you could find one that would let you play with them because the waves in the sea no doubt have an effect on how far the ball can skim. Also the technique of using it has to be learned, I gather. Overall I've been left feeling disappointed by the balls because I watched the videos from the company and was expecting something a lot faster and more exciting. I guess what it comes down to is that something like this is only as good as you make it, but don't expect too much here.