Long story short....but we rented a lake house last summer that had one. The kids loved and had a lot of fun on it.
Big problem though... one of the larger kids stuck his foot through it and I had to purchase the home owner a new one and I kept the old one.
I did repair the old one with some epoxy like glue and it held together fair for the next few times the kids played on it.
This is the one the owner had that I had to replace.
http://www.thewatermat.com/store/pro...ermat-2011.htm
They are just made of thick pool noodle material, so they do damage pretty easily.