I actually bought one of their reusable cups. Unfortunately, every time I tried to request they use it, it didn't work. Their assembly line style of makes it an impossible request. I would request it at the register, but there's no "reusable cup" option on their computer system. I would try to hand the cup to the smoothie assemblers, but since there are three of them, I would never know when my smoothie would be up, and my smoothie would get dumped in a cup before I could protest. It was useless.

I agree, but you can buy reusable plastic insulated cups from Jamba Juice (or bring your own). In fact most stores give you a discount on each subsequent purchase using a reusable cup. Fortunately, more and more cities are banning the use of polystyrene in food delivery, forcing companies like Jamba Juice to clean up their act.