Hi tbonecopper,
Outside of the suitability of a mattress in terms of PPP (which is the most important part of the “value” of a mattress) … a mattress is only as good as its construction and the quality of the materials inside it and the name of the manufacturer on a label means very little so it would depend on which of the Ikea mattresses you are talking about and the specifics of the materials inside them.
They have some better quality/value mattresses and some mattresses that I wouldn’t consider at all. There is more about Ikea mattresses in post #3 here and some of the posts it links to about some of their new models.
Phoenix