It's easy, cheap & effective platform that helps you build your business by reaching out new audience with minimum investment of time or money (as it has all inbuilt tools).
I can't think anything negative about this product because everything works as per plan! If someone wants quality traffic then he should go through quinstreet otherwise they will end up wasting there precious resources like cash/time etc.. This tool really helped me increase my website visitors which ultimately increases sales revenue from our store front page.