I think this deserves 3*if you want a child's mattress. I wouldn't want to pay full price for this product as I think the  priced now,  is what it's worth. 
It is sprung but they are not very strong. 
I laid on the mattress and I could feel it fold in the middle and I am only 10st. My husband laid down and the top and bottom lifted up off the bed. 
Hence the recommendation for young children.