I have one that I have used once in a while. They are nice, but can be pretty hot!
I used mine in a game of paintball once (bad idea, the smell from paintballs seems to never go away). I had a guy (adult) from the opposing team walk within 10 feet of me. I came out of the shadows and yelled "surrender or die" and he actually screamed! I nearly fell over laughing.
They are pretty fun.