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.
There is really only one speed on this.....very high and very loud. It is great at making anything that requires mixing to liquid form. I’ve made nut milks, soup and many smoothies. It is great for these items. I would give it 5 stars if it wasn’t so loud.