Yes, I do - they were giving them out at the CA state fair and I've cooked a pot of beans :-) Also, the Tightwad Gazette books talked about how to make them and the times for certain things to cook.
I think it is really neat, but you have to have the time to plan the meal - beans needs to be soaked and then at least reach a boiling point to soften appropriately - something like cornbread might work (or cobbler?).
I used to live in AZ and I know the sun would really cook out there - sometimes you might burn somthing - the key is to insulate so the heat as it builds doesn't dissipate.
Deserat aka Bridget
“We sleep soundly in our beds because rough men stand ready in the night to visit violence on those who would do us harm.” - George Orwell/Winston Churchill