I seem to recall that someone on here had one, but can't recall now who it was. The closest I've gotten to one is to park so that the sun is beating on my windshield and heating up my lunch.
Someone gave my father one years ago, but we did not use it much. He loved beans and I remember he sometimes put some dried beans in a bowl with water, wrap a black bag around it and put it in the solar oven and in the sun, so his beans would cook. It worked quite well!
I have not used mine in a while, but in the summer it is very nice, provided you are organized and already know by night, what it is you will be cooking and you get up early enough to put it out.
Now if you like me and have more had to plant trees to protect your house from the sun, so you can actually keep up on your utility bills and to keep comfortable, you might want to think about a good location for it.
I would have to experiment, more with more recipes, but so far, I have used it mostly like a slow cooker. The temp never got over 300F to cook super fast or actually, officially, bake anything......nah...so far it is a slow cooker, but I don't say it has to be that way, always.
As hot as my house gets on cooking days, I do anything and everything during the summer to keep my house cool. If I can start something in the solar oven, early, I do.....like, while I am doing chores anyway and if I can start cooking something that needs a lot of time to tenderize and its a rainy day, I might get it going and put it in the Wonder Bag a few hours, while I do other things. That is also a great way to save on utilities and decrease your carbon footprint. I also have a camping grill that I use when we cleaning up and have put a lot of weeds and branches to burn.....why not place the grill over the embers and throw some meat on top, while you outside cleaning? The smell might get a few family members excited and get them outside to help you out a bit.
I think most of us have gardens, so we should all have a place to keep a solar oven in the sun the 6 or so hours needed to cook something.
Its a worth while investment, provided you know what you getting and I could be wrong, but if you get what I have, you will want to plan to use it as an off grid slow cooker, which should be worth something.