Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Does not brake down protein powder

I purchased this item about a month ago exclusively to prepare and drink my post-workout protein shakes (soy milk + soy or whey protein powder).I was very disappointed to find out it actually does not break up the protein powder and it leaves lumps behind, making it very unpleasant to drink. I am not impressed by this product at all, and don't understand why other people gave it 5 stars. If you are thinking on buying this shaker to have protein shakes please do not do so, it will not break out the protein no matter how hard you try to mix it.