I'll add my two cents to this discussion. We've had really good look with this exact model. We've used it for close to half a year, every day (wife makes shakes with it in the mornings) and it has held up well. For those comparing this to the Vitamix, I think the comparison is a bit unfair, solely from a price standpoint. The Ninja we bought was about 1/4th the price (on sale) of the Vitamix. While I have no doubts that the Vitamix does a better job of getting things smooth (and it should for 3 times the price) the Ninja does a very adequate job of making smoothies and shakes.
My notes are thus: 1.) this works extremely well to make salsa and I've never noted an onion or tomato flavor in my shakes or smoothies. 2.) This will puree your smoothies extremely well. Contrary to the comparison videos, I've had really good luck with mine. I run it for a full 2 minutes, at least, on level 3. Yes, it might take a little longer than the Vitamix, but can you not afford an extra minute, really? 3.) It will make snow from your ice. Kids love this. Except when you take said Ninja made ice snow, form it into a snowball, and throw it at them when they aren't suspecting it. Then they aren't a fan. 4.) It's a ninja, and who doesn't like ninjas?
Really, though, I've had really good luck with using this blender to make smoothies and shakes (the majority of consumers I assume will use for the same purposes) and I haven't been let down. It's not a Vitamix, and you shouldn't expect that, but it is a darn good blender and for this price I think you'll probably be happy with it. It's all about having realistic expectations.