My daughter uses them a lot, but she doesn't have to worry about the cost, lucky girl. They are expensive, and quite fiddly to cook. Things like spices, tomato passata etc are measured out for you, and each one comes with its own recipe card. I cook for her once a week, and she suggested I use one of her meals each time but I was frustrated with some of the ingredients which I couldn't eat, so have gone back to cooking a meal at home and taking it over.
My daughter orders them as they are advertised as easy for those who are busy, but there is a lot of chopping and preparing, and she tends to just cook from them another dish with the ingredients the children will eat, so there is some wastage.