Generally very happy, but putting the knife unit on or off could be very difficult for some people if they don't have enough strength in their hands. A petite person or someone with arthritus would have difficulty
I purchased the 600 and took it when I went to visit my mother. She liked it so much I gave it to her and purchased another for myself. My mother and I enjoy the features of the Nutribullet. It is fast and it really breaks down the fruit and veggies to a drinkable form. Sometimes we do experience spillage. When I've thought the blade was on tightly it still would overflow. I took it on the base and the blade was loose on the cup. Not sure how that happened. This occurred a couple of times. However I still really like the product.
There are many good features...the larger size container and the more powerful motor which does the job faster and more completely, but...it's definitely more dangerous because of that added power. Need to take extra precautions to have the container on properly and don't leave unattended, can fly off and create a mess. Am encouraged by the new nutribullet rx but not interested in spending more money to replace my pro model so soon.
I wore out the original NutriBullet and loved and used it alot. The PRO is even better since it breaks down the fruits and vegetables for a nice juice smoothy. I gave this a 4 rating only because it doesn't completely emulcify it into all liquid but still does a pretty good job and much better than the original Bullet. Love it just the same.