I honestly only use it as a soundcard at this point but when I do DJ with it is really nice. The knobs are smooth, the buttons are clicky. The only complaint i'd have is that the jogwheels DO feel rather plasticy and flimsy which is that big a deal unless you are looking to scratch than this definitely wouldn't be for you.
When I realized that I need to buy some DJ hardware I deeply searched for the right hardware. So finally I decided to buy Numark N4. That was the right choice. There is no problem with connecting it to Mac OS/Windows, buttons, knobs work perfectly. I'm very pleased working with this controller.