Instruct: Classify the given Amazon review into positive or negative sentiment.
Query: Unreliable product - don't waste your money!

I received one as a Christmas present last year, which malfunctioned within a month (would power up then turn off for no reason). The company gladly sent a replacement which malfunctioned after about 2 months (made a grinding noise and would only brew a few drops). Tried again with a 3rd which worked great for about 6 months, then totally quit - won't power up at all. I used filtered water every time, so tap water was not the issue.It's convenient when it works, but this needs to be refined into a much more reliable product. Also, I was only able to find 1-2 K cup varieties that didn't brew weak coffee that tasted like hot water. I tried dozens.