Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Uneven heat

I had been using a thirty-year-old 4 qt crock pot and loved it. So I got this one. Big mistake. I tried to make a chicken dinner in this pot, let it cook for the appropriate length of time, let it cook for an additional hour, and then the chicken was still not done. Maybe it's not the brand but rather the shape of this crock pot - maybe it's better to have a round crock pot and not an oval one. Either way, I want another crock pot like my old one!