room addition with the Nostiel System

I am considering a lowcost way of adding another room to my 2-bed/2-bath CBS (concrete/block/stucco) house. I've looked at the Nostiel pre-fab system, which appears to be based on polystyrene/aluminum panels and advertises a cost of $25/foot. Anyone with any experience using this sytem? Looks like it might fit the bill for me. Any caveats here?

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