Anyone use the Saraha Vest from Joe Rocket?

I just bought a Joe Rocket jacket/pant set up and the sales guy showed me this Sahara vest that you can wear under your jacket. It is used to make you much cooler during the summer months. I guess you get this thing soaked with water before you ride than put it on and it will keep you cooler while riding in the summer heat. (I live in Phoenix). Just wanted to see if anyone else could give me their opinions on it. Did a search but did not find anything.

Thanks!