This is quite exciting in that it removes plastic waste. I see no reason why different companies can't make different shape ones to maintain their lock-in. I expect a knock-off market to pop-up, but that exists with plastic pods too. It's a step in the right direction at least.
Good to see Keurig try to cut down on plastic waste, but if they really wanted to make an impact, they could open-source the design of the pods so all the alt-cup manufacturers could switch as well. It may be counter-intuitive, but the more options customers have, the more machine sales and goodwill Keurig will create.
Same size as paper ones. Thin, perforated metal. Came in two gradations. Taste-wise, couldn't tell the difference. When opening to clean, it slid off so you could wash it, then compost the coffee as usual.
Pretty handy. But somehow, I managed to dump them away. Went back to paper.