Yup. The cost of the materials it contains is important. From the description, it lowers the amount of energy it takes to produce compared to standard glass. I'm not sure how large of a component of the price of glass the energy it takes to produce it is. If it is cheaper and stronger than 'standard' industrial glass, it's a win. If not, it may have specialized applications. Would also be interested in knowing if the resultant product is, itself, recyclable. If not, then you have to take materials into account again. Would love to have affordable shatterproof containers because glass is really easy to sterilize and clean.
Since recycled glass is added to make new glass, what happens when old glass or new glass contaminate the recycle stream?
Can old and new be mixed? Keeping the recycle streams separate could nullify savings and potential recycleability.