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I'm a healthcare professional and bought this after researching the competition (i.e., "Vita-Mix). After reading through a gazillion comments and reviews (including CR who rates the Ninja #2) I opted for the lower priced Ninja. I have used mine twice a day for the 6 weeks I have owned it, I use it for making smoothies. I blend for health, I have a morning fruit and berry smoothie and I have an afternoon veggie smoothie. Blending is a really convenient way to get in all your servings of fruit and veggies each day without removing the (very important) fiber. So far, I love my Ninja. I have had stuff made with a Vita Mix in the past, but have never done a side by side comparison, though I can think of a few differences that are meaningful for me. One, the Vita Mix generates heat. They use it as a selling feature, that you can use it to make soups, but I like my smoothies cold, so it's not something I look for in a blender. Secondly, Vita Mix seems to win in all the comparisons with Ninja on smoothness, or thoroughness of blending. The only reason I knocked one star off the Ninja is because I have noticed that my smoothies are a bit chewier after several weeks of blender use. I attribute that to the fact that Ninja relies (apparently) on their sharp blades, which naturally dull with use-especially when blending frozen berries or ice (which both of my smoothies contain). I've noticed a subtle change in texture, no chunks, but definitely not a fine blend. My understanding is that Vita Mix has dull blades that work for years, they do not rely so much on sharpness as they do on speed? The other thing (in addition to heat) that you get with a Vita Mix is aeration (foam), which I do not notice with the Ninja. My smoothies are full of fruit and veggies, so they are full of fiber. If you are okay with having some noticeable fiber in your blend over time, the Ninja is a great deal at about 1/5 the cost. If that matters to you, expect that you will have it in time (I started to notice it after about 25 blends). The blender cleans very easily and is simple to use. I've never had to remove the top to tamp stuff down and I use 3 cups of leafy greens like kale and arugula, as well as whole carrots, celery, apples, and never have chunks. Overall it's a great machine. I cannot rate longevity since I've only had it 6 weeks, but so far I'm very pleased.
Update: It's January 2018, I owned the Ninja about 3 months and ended up getting a Vita Mix. I still stand by my original review, but there is a difference. The Ninja starts out pretty great, but then over time things do no blend as well. I drink 2 smoothies a day (one veggie, one fruit), so I use it a minimum of 2x a day. Over time I started calling my Ninja smoothies: "grainies." The blades start out very sharp, and the technology depends on that, but they dull with use and it shows in the results. The Vita Mix does not depend on blade sharpness, but power, it pummels everything to pieces (itty bitty pieces). I am amazed at the flour I can make with it. Also, the heat i mentioned is not a factor but a feature. Most things are blended in less than a minute (35 seconds often), so nothing really gets warm unless you leave it on in order to generate heat. The Ninja is a good blender, especially for the cost, but I don't think one can fairly compare it to a Vita Mix, it's like comparing apples and oranges.