Amazon calculates a product’s star ratings using a machine learned model instead of a raw data average. The machine learned model takes into account factors including: the age of a review, helpfulness votes by customers and whether the reviews are from verified purchases.
This product actually worked quite well, but then burned on on its 4th use. I was very careful to monitor for over heating, but it still burned out. Good thing I have a hand grinder I could use t finish the job!