I bit the bullet and bought one last week after Quakerstack talked about it on here. I got it at WalMart for $20.
I put it in the middle of my boat while I was working on it the other night... turned it on when the skeeters came out, and after about 10-15 min they were all gone.
I was out there til about 10, so for 4 hours it kept me clear of bugs. I think that's how long the first mat lasted too. I think the propane tanks last about 10-12 hours, and I guess a mat lasts 3-4... maybe that's why it came with 3 mats and 1 propane tank.
I'll be buying another to give Tiffany. They eat her up, but don't bother me... ever since I got the Anthrax vaccine, nothing bites me... when mosquitos get through my thick skin, they usually end up dying before they ever get off my arm (and not from me smacking them)..