Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Great idea, bad implementation

Got the product, plugged it into my car, everything worked. Good news so far. The second time I used it, the USB ports didn't work. Maybe I blew a fuse on it, except the 12 V sockets were working. Just a defect in the USB ports. I got a refund, so the seller was great about it. And I know manufacturing is never 100% perfect, but I wasn't willing to try again. Bought something else.