I keep seeing these in the shops, but surely they are just like ovens? So if you already have an oven, why would you want to buy one?
I get the point that they cook food really slowly, so you can put a casserole on at lunchtime and it will be ready in the evening, but couldn't you just do that with your oven on a really low setting?
Lots of people have bought them though, so I must be missing something...