We use our NutriBullet daily for protein shakes and it a well-designed and easy-to-use product. If it is durable as well, we'll really rave about it! One design suggestion is that because the fill-line is critical to the operation of the unit, that line would be prominently marked completely surrounding the glass -- more that the little sign that exists.
Works great. I did lots of research and decided this one over all, including juicers. I like smoothies and this one with such a great price (search a little) can do it all (fruit, veggies, nuts, dry, etc.) The only downfall is you need to pay attention to the max line. As long as you don't fill liquids over that line, there's no leaking. This works for me.