I bought one about six months ago & think it is fantastic, fun, and makes me feel like I'm getting somewhere with this prep stuff.
It works pretty much like a regular (electric) slow cooker, cepin you put it outside and let the sun do the cooking.
The only thing you have to attend to is the movement of the sun. You will need to move the oven with the sun to keep the best heating. Think of someone at the beach with one of those reflectors under their chin to tan the neck. The sun oven works like that.
Two quick things: the outside temperature doesn't matter. As long as the sun is shining, you can cook even in the snow. The other thing is that you'll need to exercise some common sense when opening and closing the reflectors - looking right into the reflected sun isn't fun. Now, if I had had a bit more common sense, I wouldn't have seen spots. You won't go blind, of course, but experience is a good teacher.
Beef, chicken, pork, veggies - cook just as you would in your slow cooker, oven, or stove top. All the meat I've used is, as they say, 'fall-off-the-bone-tender'. It really is. I feel I've made a good investment. (I don't know the status of the discount.)
Now, only 538,354 things more and I'll be READY!