I haven’t used it, it was sent to my grandkids.
Their ages are 13, 11 and 9. All three of them can use it to make their own smoothies, so it can be said; so easy a kid can work it.
My only issue, it was supposed to be a Christmas gift.  It was delivered in a box with the Ninja name all over the outside. 
No secrets there.
It’s perfect for what it was purchased for.