The concept is flawed. Getting random feedback from random people is not at all useful. Feedback needs to take into account the target users and the goals of the design. The designer needs to ask specific questions, not just "what do you think?". Maybe this product would be useful if users could put out a call for people who meet certain criteria (i.e. music-lovers, 25-40), and then focus their attention on a small set of questions. In this way, there's a possibility of getting something useful to go on.