I have been using my vitamix S 30 for about 5 months now, usually twice daily. I have been using these 20 ounce cups every day for smoothies, and I really think it's a great product. The way that the cup is shaped is designed to assist gravity in making sure all your ingredients stay at the bottom of the cup. I fill the cup with frozen ingredients, greens, and sometimes even dry oats, and my smoothies always come out really well blended, and anything stuck on the sides slides down and mixes. I do sometimes have to give the cup a good shake before blending because the frozen fruit likes to freeze to the cup with almond milk, but this is nothing to do with the cup. The plastic feels substantial and good quality, and cleans easily. They rinse well, and also clean nicely in the dishwasher. I have used lower quality personal blending cups (and blenders), and the thought that went into this design is really evident with consistent, daily use..