How would you rate this mattress?

Hi John and Ryan
I wish I could afford one of your low polyester pocket sprung natural mattress. I have been looking for something similar within my budget.
Could you tell me what you think of the Silent Night knightly 2800 natural Ortho mattresses. I can get this on a deal for £457.
Any advice would be great, I would be buying a sprung slatted bed frame also.