The Ninja Foodi NeverDull System is awesome!  It is more on the larger size, so takes up a bit of space on the counter.  However, you can use it with any knife for sharpening. The sharpener is easy to use by just swiping the handle down and letting the system do the work.  The Ninja knife that was included is very nice and a great added bonus to my cutlery.  I would definitely recommend for ease of sharpening!